Everyman Sleep Cycle with School. Schedule Help?

Hello :3
I was thinking of attempting a polyphasic sleep schedule for my junior year in high school. I'm taking 5 AP classes, one of them being an art class. Having extra time to work on things seems like it'd be very helpful. Since summer has started I thought trying this out while I'm free to be lazy and tired would be a good idea XD
Now, my school runs for 7 hours, and I need about twenty minutes before and after school to get ready and get home. I would like to try to avoid taking a nap at any time during the school day, but the gap is pretty long. I thought maybe the Everyman 4 schedule would work better and have arranged the following:

Core 2:40am-7:10am
Awake ~8hrs
Nap 3:10pm (estimated time, whenever I get home from school)-3:30pm
Awake ~4.5hrs
Nap 9:00pm-9:20pm
Awake ~5hrs
Total Sleep Time: 5hrs10min

This is my first time attempting a polyphasic sleep cycle so I wanted to make sure this schedule would be okay :/ If I have to get a nap in school time it'd take up my entire lunch period so I'm just trying to avoid that.
Also, once I decide to start attempting the sleep schedule (it may be in a bit, I'm kind of sick and mentally dying right now DX), does it matter if I start with a nap, or do I have to stay up until my core sleep time and start there? That sounds like a noob question, sorry ;~;

Thanks~

I don't have experience with Everyman 4, however I have done Uberman and am currently biphasic (some days triphasic when my schedule dictates). It's definitely a good idea to start this during the summer. Instead of going directly into Everyman 4, I would suggest that you start out as Uberman for 3 or 4 days (or as long as you can) and then jump into Everyman. When I was ending my Uberman phase, I switched to Everyman with a 3 hour core and it felt amazing. In doing this, you'll cut out at least a week or more out of your adaptation time.

It's worrisome that you'll have to go over seven hours without a nap in your schedule. Everyman is more flexible than Uberman, but when I skipped or postponed a nap, it felt like the world was ending! By the end of that 7 hour period you're going to be exhausted, so if you are driving yourself home from school I would strongly advise napping during lunchtime. It also goes without saying that since you'll be exhausted at the end of the day, your performance in your later classes might suffer. Just be aware of this fact when planning your nap schedule.