Fairly last minute based on courses in a particular major and location. We did not talk about colleges at all until mid-junior year and certainly did not focus on Ivies. You are stressing in 8th grade about stress in 11th grade 
Double stress!! Try not to think about it too much for a couple of years.
And Sherpa makes a good point. Many come on here saying that since age 5, Harvard has been their “dream.” It is a little like wanting to be a fireman when you grow up Not that there aren’t mature reasons to apply to Harvard…but not at 5 and not in 8th grade either.