You can book a date for visa interview before 90 days of your planned travel and it should be done as early as possible. Usually it takes 6-8 weeks to get the visa approved and depends on numerous factors such as your regional consulate, admitted university and so on. As more admits start rolling out with time, sometimes it is hard to get a comfortable date therefore plan ahead.
While booking the your visa interview date keep the following things in mind as a checklist,
You will also need to take biometric photos for your visa interview. You can find more information on the student visa process here