Two factors affect the speed with which you can see leads increase: your current inbound marketing efforts and how much you're willing to spend to increase leads. For example, if the current status of your inbound program is that you have none- you'll have to start from scratch to build content and infrastructure and it might take up to six months before you start seeing leads coming in. If you have an existing program, it will be quicker to get new leads. If you're willing to spend a little more upfront to build out your program quickly (or enhance your existing one) that'll also cut down on the time it takes to get new leads.