Question
Is there any way to effectively do a September fescue overseed in North Carolina, and as soon as the fescue has germinated and been cut twice also apply a pre-m for poa (annual bluegrass) control? The heat in NC doesn't allow for seed germination much earlier than mid-Sept. Even if there is some poa germination in Sept (usually more so in  Oct-Nov), could the poa pre-m be effective enough to cut down the invasion of poa? Do you have a better idea or solution?

I just need this fall to hopefully thicken and fill in most areas of my lawn wioth new seed, then I can devote the next few falls periods to complete poa eradication.  TIA.  

Answer
Yes you can do that. Once grass plants have germinated they are no longer susceptible to pre-emergent herbicides. Check lable of the herbicide when it is safe to apply to a newly seeded lawn. It usually says so directly on the lable. If not, then following your own guidelines should work.

-- Kenneth