Well, my first recommendation letter was from my current employer who I've worked for since 2008. And the second, S.B., wasn't one of my professors but she's a speech-language pathologist I observed a few times while completing my clinical observation hours at university. We developed a pretty good relationship during that time and since I got to know her better than any of my former professors, I chose her to write the letter. She's employed by an elementary school, not the university, and she did explain to me that she was very busy with progress reports, evaluations, etc. I thought a week was plenty of time but looking back, maybe I should have made it two weeks or more... then again, this was my first time requesting recommendation letters so it's all a learning process.
The admissions tutor (at Sheffield) I've been in contact with hasn't given me a deadline yet, he just basically told me that in order for my application to be considered they have to receive the second letter of recommendation, which is obviously understandable. He told me that he's read my application with interest. City Uni London doesn't even look at any of the application materials until everything is received, or so an automated e-mail message from them told me. So far, I'm impressed with Sheffield more so than City. It was nice to hear from a person who had interest in me rather than some automated e-mail. I wasn't expecting to hear from anyone I was pleasantly surprised by that.