You should send me in one email at least two weeks for your first deadline a copy of everything you will submit with your application (cv, transcripts--unofficial is fine, essay, statement, research proposal, GRE scores etc.). In this same email, tell me what your earliest deadline is. In most cases, I will write one letter, and I will finish it before your first deadline. In the same email, you should tell me (even if you have told me before) all the places you are applying (or a representative sample at least), and anything I need to know about where you are applying (no need to say more about math grad schools or math academic jobs other than listing the institutions, but tell me about special programs, etc.) and who else is writing a letter for you.
Please let me know if there is anything you think would be good for me to address in your letter, or anything particularly positive about our mathematical interactions that you want to remind me of. If I have written a letter for you in the past, it can be especially helpful to clarify what is new since the last time I wrote you a letter.
The letters will be sent by Pam Brentana in the Harvard Math Department. When you list me as a recommender, you should put my email address as brentana at fas dot harvard dot edu, not my usual email account. At least two weeks before your first deadline, send Pam (at the above email address) a list of all the places where she will need to provide letters, with deadlines, and note whether she should get an email with a link to upload to letter or she needs to proactively email or upload the letter (and if so, where to). Please particularly let Pam know your earliest deadline. It is helpful if you can put this information for Pam in a spreadsheet, or at least in one comprehensive email (though we do understand additional applications do sometimes get added later).
If the deadline is getting close, and none of your letters from me have been submitted, feel free to remind me. If some letters from me have already been submitted, please reach out to Pam.