You can start with whatever fires you up, whatever excites you, whatever fires your indignation, and put your energy there. And it's as good a place to start as any. I think that if it speaks to your heart, if it engages your imagination, if it makes you want to get out of bed in the morning and do something, that's probably the best place to start. And that to me is the inside of the political movements that I was part of. Organizations come and go.
Intellectual theories come and go.
The power to change the way people think and what people do comes out of small groups of people who care enough about something to try something new. And that can be done any time. Embedding yourself in history, in a way, to go with those new ideas and then formulate them yourself. There is an intellectual tradition of political activism that isn't as strong in this country as in many others, and often needs to be re-invented and rediscovered in each generation. But, yes, it helps if you know that other people have thought about these things before you try organizing.