So on with my dilemma...
My wife and I have just bought a home this past winter and while we love the house, our fondness for the current state of the lawn just isn't there.
The lawn is full patches of dead and or thinning grass. So naturally I plan on spot treatment and an over seeding as the lawn is not very thick. My understanding is that I need to get a crab grass preventer down very soon - (I'd like to do this as soon as possible). By now you may be seeing my problem.

How do I apply a crab grass preventer and not rule out over seeding and spot treating very soon after applying the crab grass preventer?
Hopefully this is possible, and thank you in advance!
-Brad Hardy