When does your school day start and when does it end

I don't want to sound ungrateful but I go when I want (mainly to socialise) it's supposed to be from 8.30 to 15:30 but it more like 12:00 to 15:30 for me plus the extra bunking hours I do occasionally, oddly enough my grades have never suffered so ╮(￣▽￣)╭   reply