School begins at 8 o'clock every day. Many students think that it is too early, because they must get up very early. Secondary school students go to bed late, so they sleep little. Primary school students are not so tired; getting up early is not very much hard for them, because they are already sleeping at 9 or 10 in the evening.

If someone must travel a lot to get to school, they need to get up at 6 or even earlier, and if they have zeroth lesson, then even more earlier.

On the other hand if school began later, parents could not manage to take the children to school, because they must go to work by 7 or 8.
Teaching would be finished later on the afternoon, though it lasts till 3 even now some days.
Additionally, zeroth lessons would be earlier just the same way. So my opinion is that school-day start time is just OK now.