My German high school started at 7:45 am.
7:30. (Sieben Uhr Dreißig - darauf scheiß ich!) With 5th (and maybe 6th as well?) formers starting school with the 2nd period.
It was some special deal due originally to Deutsche Bahn timetables and the fact that it was the most easily reached
Gymnasium for residents of Maintal... though by my time, very few people in Maintal sent their kids to Frankfurt from 5th grade on, instead attending the local Gesamtschule and transferring in 11th, so by then it was really just a case of inertia/tradition.