Hello NNS.

Some questions first:

1. What do you mean by strong idea? Why is it strong? I am not knocking you on this. I myself do not share the disdain for ideas when compared to execution. We know it's down to the execution, but give me a great idea any day of the week.

2. What is your domain experience in regards to the idea? Are they in the same domain?

If I can answer the second part of your question first: "...attracting co-founders and talent to work with you."
Before I go into the main body of my reply, if by co-founders you mean a programmer, then my advice is don't go down the path of something like:

"I have done the hard part, you push your paying jobs aside, sort out the code and prepare yourself for the type of riches only those standing on checkered floors are accustomed to. 5% of the business sound about right?"

You may not even need a programmer off-the-bat anyway. The tech isn't the solution. The tech is a scalable efficient conduit for the solution. Customers couldn't care less if their woes were alleviated and goals were attained via tech or a rubber band.

Anyway, how to attract:

You know the cliche sales question "Sell me this pen?". How can you sell the pen to someone who doesn't give a stationary? You can't, and you don't, because you don't know what need they have for the pen, what it brings into their life, etc, etc, the value of the pen to them. Same thing with attracting co-founders. If you attempt to attract them straight away, with nothing tangible to show, then you have one main option:

1. You need to find out what they think, what they feel, where they are coming from, where they currently are, where they might be heading to; in regards to your strong idea. If there is resonance, if they are on a path that suggests the journey could be shared, for they for a period of time are heading in similar directions, then there is a chance. However this chance is small unless you can show various qualities they are looking for. Honestly I don't even know the qualities really, maybe a few at best: hunger, tenacity, vision, self-belief (a stop before it goes into self-delusion), point to prove (to themselves), etc. I just summarise it by saying, they want to see if this person is just a talker or a doer. Have you got it within you to stay the course? Are you going to jump ship at the first sight of an iceberg or are you going to stand your ground and pull out your violin as the iceberg approaches?

Some people look for passion. I don't. If that works for them, fair play, who am I to say otherwise? However for me, passion? Nah. I leave passion for the Don Juan's, the Cassanovas and the Lotharios, for I have seen the passion in the divorced couples, in the broken hearts, and the jilted lovers. You'll need to find what fuels you, and make sure you to show it to others, not just in words but with deeds as well. None of this rubbish fake it till you make it, then the following week you're sat there with Impostor Syndrome. You be by doing, and do by being.

Anyway, as you work on your idea, moving it away from just in your head into something others can evaluate, you will increase your chances of attracting co-founders et al. I personally wouldn't bother with attracting anyone. Just get your head down and work on your self, and thus your idea. As this process occurs and you obtain targeted feedback, and let relevant entities know of it, you will start to attract people. But it needs to be targeted feedback. Just as you don't ask your mum as described in The Mom Test, because you she loves everything you do; you don't ask your dad either cos it's just not good enough, it won't work, etc, etc. No point asking anybody too close to you, bar a select few who don't let feelings come in the way. No point asking anybody other than assumed target audience, and even then pinch of salt, and a mixture of early adopters, laggards, etc, etc.

As for the first part of your question go about "founding your startup". I think you need to be wary of Survivorship Bias, Confirmation Bias, etc. Stay away from the "I went to bed, woke up, boom, overnight success-ed it" brigade. I have my own biases. I am filtering reality to verify my perception and my place within it. I read some of the other comments, informative and insightful. Sell or build first depends on many factors: to who, what, where, when, how, etc. I looked into this for quite a while, too long to say Lean with a straight face really, and I kept coming back to my own bias, am I deluded, am I lying to myself and do I not even know it, how little do I know, etc, etc.

Based on that, and the riskiest assumption out of the lot being do I really know, I have to say that you start by looking at the problem. My primary domain experience is in marketing, and the first thing I always do is audit the whole shebang. You have to find out where you do really stand, what do you really know, who else is standing in this space, what are they saying, etc, etc, in order to then plot a course to where you want to be.

Forget solution, tech, marketing, forget customer discovery as well. The first thing you need to do is be equipped with knowledge to not only stand on slightly firmer ground, but also when customer discovery does take place, which it needs to very early on, is be able to sort the wheat from the chaff, otherwise you are not really in a position to ascertain the value and the validity of the information obtained. You see it quite a bit in customer discovery classes, people getting out of the building with no reason nor rhyme as to who they actually interview. They interview every Tom, Dick and Sally, with no regards to if their opinion is even relevant, let alone valuable. Now there is a danger here in that, you don't want to be biased in that you seek to verify your research, but then it comes down to if you want to 'prove' you are right, or if you want the truth.

In the customer discovery you seek to not only ascertain if the problem is validated, but which target audience seems the most viable to go with first. I prefer not to go in hard on one segment, unless I have a strong thought/feeling that this is the segment afflicted with the problem. It depends really, on how much knowledge and insight you have, there are no real set in stone rules, just don't tick boxes for the sake of it, nor ignore a box solely on the basis of your own 'knowledge'.

When it comes to actual problem evaluation, look at root causes, factors, pain points, scenarios, etc, as well as noting the language used for usage down the line in various things. Use qual and quant methods as well as probing from multiple angles, looking for consistency and coherence (or inconsistency and contradictory), when it comes to problem severity, frequency, emotional response, etc.

After customer discovery, I'd say take a quick look at the market landscape, not too heavy, for you can end up being influenced by what others are doing, and who knows, your approach, your idea, etc, may well go far beyond what others are doing. Stay in contact with those you interview, certainly the ones who display certain early adopter traits, but you also need some laggards, and some that resonate with the vision (the end goal), for problem is just a roadblock from A to B.

I'll skip some of the other things I would mention here, message is too long. So:

Ascertaining market demand: all for it, but not some lame landing page 3 lines and a sign-up box, that shows a lack of insight, lack of understanding, lack of resonance, et al.

Building MVP: minimum is not in a bubble, look at the market, the competition, the audience expectations, minimum is fluid and ever increasing in some areas. You are below minimum if you can't hold your own against the competition on one front at least.

As you can tell from the other replies to your question, there are no absolute truths, so whatever your journey is, I wish you luck.

Cheers, Ace.