I have seen the process take 4+ years with elite recruits who had been dealing with coaches since the 8th grade. I have also seen recruits in the last few months of their senior year get really lucky and find a program that needed someone. They were very lucky a scholarship was available, they had the grades and some how they were discovered at the last minute.
The average recruiting process lasts around 2 years. You should start the process in your sophomore year (or your freshman year if you are an elite athlete). Expect to be spending the first year researching schools, getting coaches what they need to make initial evaluations and getting your list of 15-25 schools that are the right fit and showing some interest in you. The most difficult thing in this phase is determining if you are being recruited.
Once you have schools interested, your Junior year and the summer after is where you begin to see what schools are going to be most interested. You will be attending camps, hopefully visiting schools and playing in summer tournaments where coaches will be making further evaluations. By late summer leading into your senior year, you should have a really good idea of your top 3-5 schools. Your senior year is all about official visits and getting all of the final paper work done for early signing period (if you are signing in November) or in the spring for the regular signing period.
The above scenario is an ideal timeline and by no means the only way to get recruited. The one sure thing in recruiting is that almost nothing goes as planned. If you don’t fit the above timeline you need to know where you stand and what you should be doing. I am happy to help, you can contact me on Google+ where my email is available or create a free profile on our site and one of our national scouts can talk to you.