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
I have 5 letters of recommendation on file (overkill, I know), and all of my initial requests were by email. I think asking about officehours is a great idea, or alternatively, you could do a phone or skype call.
Yay! Some new folk!
Thanks again to Selene for being a part of last night's officehours. And of course, to David. I love that you all do those things for us.
... directed to David in his OfficeHours this Wednesday (the last for ... .com/discussion/#/discussion/18349/last-office-hours-of-the-year-weds-dec ...