I'm hoping I timed the pre-emergent this year. I put it down the first week of April since we had an extremely cold March it seemed. I've heard if done to early or late it may be ineffective.

Based on this article from OSU, I think I got it right.

http://fairfield.osu.edu/topics/horticulture/news/apply-crabgrass-preventer-now-1

I used some of the post emergent last year and did notice it turned the leaves dark but it was probably too late when I did that.

Would now or later in April or May be a good time to use the Ortho Post emergent spray?

Growing grass as long as I can right now also.