Where are you located?

PreM won't stop the Bermuda from spreading underground

It will stop more Bermuda germinating from seed though.

I am just north of atlanta. The pre emerge is for the crabgrass that can get out of hand during the dog days of summer.

Indeed it will help prevent seeded bermuda & that nasty crabgrass

I would apply preM to control what's coming up ahead and then apply the overseeing in the fall. If you have small bare spots , you can go around that with the PreM and separately seed the area. Depending on how hot it is during the summmer , some of the fescue won't establish strong root system to sustain the drought and will die early.

Seems like Atlanta would be a tough place to grow a cool season grass. What does your law care routine look like as far as fertilization/irrigation/pesticide during spring/summer?

Ive learned a valuable lesson living here in georgia over the last 10-15 yrs.Cool season grasses are fine here in the winter, or early spring .To have cool season grasses thrive in the summer heat you have to have 1. ALOT of shade,2 an irrigation system and 3.a premergent down.I just went with bermuda and have had the nicest lawn ive had in years.Never will waste another dime on those expensive bags of grass seed.

The warm season grass zone is moving north fairly quickly.