What to send with the ask, and how far ahead

Ask at least a month out, and further ahead in the weeks when everybody else is asking. A rushed letter is a general letter. Ask in person or on a call if you can, then follow it with everything they need in one message, so they never have to come back to you for a document.

That message carries the deadline and how the letter is submitted, the course and institution and one line on why that one, your CV or transcript, and — the part people leave out — a reminder of the specific work you did together, with the piece attached if it still exists. You are not writing the letter for them. You are making it possible for them to be specific without digging through their own files.