Varies Uni to Uni, but I'd assume between 8am and 9am is the norm. Your earliest lecture varies from course to course as well. I had days where I had to be in at 9am, other days at 12. The day could be as simple as "Go to lecture/seminar at 10am; go back to halls/library", or "Go to lecture at 9am-11am; library/lunch for an hour; 1pm lecture", or even "Go to 9am lecture; 3 hours off; 1pm lecture; hour off; 3pm lecture; 4pm seminar".
Depends on your course, Uni, and if you are able to choose your times (I could for Spanish) or if things are timetabled (as my Italian and History courses were). Don't panic so much, and change your lifestyle. After Uni, you're probably going to look for a 9to5 job, so get used to getting up before 9am while you can!