Little late to be seeding in CT no?

I think borderline, I've read that mid October is about the cutoff. The temps are still in the 60's during the day and high 40's/low 50's at night so I think it would be ok to seed at this point.

j4 is right. You're a full 2 months late to be reseeding. Mid Oct may be the cutoff, but the window opened August 1st. Had you started then you could have had new grass up by mid August, evaluated whether you needed to add more seed in the thin areas, and gotten that done by mid Sept. At this point you will have no chance for a do over.

Not only that your lawn company finished a little early. Is your grass still growing enough to be mowed every week or two? The last fertilizer app should go down after the grass stops growing. Whether that is early Nov or late doesn't matter. Let the lawn tell you when to fertilize.