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I have a few questions... I want to work in public interest and I am focusing on two markets for this summer. I submitted 5 applications in market A and 5 in market B. All my applications have been sent in the last 14 days. I've heard back from 3 of the places to which I applied in market B, and none of the places to which I applied in market A.

One of the places I heard back from told me they will get back to me about an interview once my grades come in (late January).

With another I have an interview next Friday.

With the third I was told that they'll be reviewing requests by late March, and that I should let them know if I need to hear from them prior to that time.
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Given the timing of the other two opportunities I feel like it's pretty likely that if I do get an offer from one of them, it will be well before late March. How should I go about handling it with the third employer?

How long should I wait before following up with places that haven't gotten back to me?

How long do I have to accept an offer once it's made to me?

Do you have a career office that you can talk to? I'm guessing from the large number of views but lack of responses, people are trying to help, but your question might be too nuanced to give any real/helpful answers.

Not sure about following up, but I received an offer from a PI organization that stated I had 1 week to respond. I don't know if that's the norm or not though.