changing photoperiod time frame

Do you think it would mess up my pants that have 8 weeks of flowering if I moved my lights-on time from 4:30pm-4:30am to 9:00pm-9am? I would extend the dark period by 4 1/2 hours to get the lights on at 9 pm and then continue the normal schedule. I want to do this because we have some hot days coming up and temps could get very high during the day. I dont want them throwing hermies because i messed with the light schedule though

Nope. Should be fine. Personally i would run a longer night rather than a longer day, to transition them though.