I would ask at the beginning of the semester because as _Seeking Perfection_ said they're not grading assignments at that time and aren't as busy. This way you also have plenty of time to meet with them during officehours if you'd like.
Honestly, your score is great, and I think your time is better spent on softs (which will definitely matter for t3). Hone your personal statements, go to officehours to maximize your LOR, and get involved in your community