IIRC, schedules are finalized about 90 days out. Up tomthat point, there could be a slight schedule shift in either direction. Happens all the time. Could be 5 minutes, could be an hour.

I booked a December trip last June, not 2 days later they shifted the TATL leg back an hour. A couple weeks later, they moved my connecting flight to that one forward an hour. I could ask for a re-route, and they are pretty good about that provided the start/end points don’t change. (IIRC something about a 150 mile rule, but no idea how/when/if that plays into it all.)

The only reason I have yet to seek a change is the connection is through ORD, and well, the Flagship Lounge beats what they have going on at DFW right now by a country mile. If the FL was open at DFW, I’d have switched the connection as soon as the change happened.