Light schedule

I wanted some input on how I should schedule the 18 hours on and 6 hours off light schedule for my plants. I work 5 days all at 1:00pm till 9:30 pm and I was wondering how I should set up my light schedule because I have a potential variable that could cause me

problems.

Due to space I have to grow in the same room that I sleep in and of course during the nights it can get pretty hot so I let my ac unit run on a mode where if the temperate gets higher than what I set it at it will kick on.

So Im kinda confused on how I’m gonna set it up because I’m also not sure if you have to water more than once per day because if that was the case I’d wanna set it up to where I’d water when I wake up and before I go to sleep.