When is the best time to reach out to potential advisers while applying to PhD programs?
1) In my experience, it’s never too early to reach out to someone you’d like to work with. I think it’s perfectly reasonable to send the professor an email indicating that you’re considering applying to their group and that you’d like to hear more about their research &amp; determine if you’d be a good fit. This saves you both time if you find out it isn’t a good fit.

2) I don’t think you need to worry about getting “locked in.” The professors will understand that you’re exploring your options, and you can emphasize as much in your conversation. You’re just exploring a potential collaboration - you’re not committed until you accept the admission offer.

3) A personal relationship with a potential advisor is, in my experience, a great asset during the admission process. Again, they will understand that you’re exploring multiple options. Just conduct yourself respectfully and professionally and there should be no hard feelings. (Thank them for their time, be up front about your goals and intentions, etc.) And besides, this won’t be time wasted: even if you end up choosing another University, there is always the possibility of collaborating with or being co-advised by the other professor.

**Of course, this advice is subject to any professor’s expressed preferences. If they say “let’s talk after admission decisions” - that’s fine! If they say on their website “feel free to contact me if interested in joining my group” - great! If they don’t respond to your initial email (perhaps +1 reminder email) - no worries!