What
@jelly-b said.
To add on- Interfolio is the easiest way to send your letters, I believe this is for both your professor and you. Interfolio tells you how to send them a request to write the letter. They type it up and email it back to Interfolio using the link you've sent them. Once they're done, you can choose to send them to multiple schools or hang on to those letters until all of your letters are in.
If you are worried about expenses,
Scholl is the only program that requires you to have letters in before they look at your app. Every other school asks for them after acceptance. You can turn them in early if you'd like but it is not a make or break deal in most cases.
If money is tight, make an Interfolio account but don't send letters until after your interview to your top pick.
I did not send letters until after I recieved an acceptance from my top pick. In your acceptance letter, one of the requirements will be to send in
final transcripts as well as
recommendation letters.
I forgot how much it is to send each letter but I only had to send 1 set out.
