Changing light cycle mid flower

I've had some plants growing for almost 2 weeks now in 12/12. They start at 7am and go off at 7pm, but its been getting too hot during the day in the room because its getting hotter outside. last year i ran my plants at night to avoid this problem in spring/summer but totally spaced it when i planted these guys 2 weeks ago.

question is, would it be safe to switch them from their current 7am-7pm cycle to something like, on between 6pm-6am? basically the exact opposite of what they've been on for almost 2 weeks now. if not i'm afraid its going to be too hot in the room for them. anyone ever tried this? thanks..

The best way to go about it imo is to do it gradually. Like change it 1 hour every day till you have it the way you like it. I've had to do the same thing before..