changing lighting schedule?

A buddy of mine has his 1000 w hid turning on at 11 am andis turning off 11 pm 12 hour cycle. well summer is close and it's getting hott. he wants to change the cycle so the light comes on at 8pm and off at 8 am instead how would he transition this to avoid stressing or herming his plants is this even a good idea well i basically just told him to make it so the light just dosent come on until the desired time 8 pm. is this ok or does any one have better ideas? _R

ive changed te light schedule in t midde of flowering several times and never had an issue.

cool well thank you for the advice i never had any problems either but my bro is freaking out lol thanks for the good reply time +rep