How long should a reference take to respond?

Always ask someone if you can use them as a reference. First, it is polite and gives them a heads up that they will be getting a call and/or email (they may not answer the email if they think it is bogus). Second, you need to make sure that they are willing to be a reference for you. I have had people use me as a reference because we got along, but because they were very bad employees that I would not want to work with them again, I could not honestly give a good reference. So, I chose not to respond to the inquiry.

The short answer is same day.

You should make sure, before you give the name of a reference to a potential employer, that the reference is willing to speak favorably on your behalf. Don't assume that any previous boss will want to do this. You need to maintain a relationship w/ all your references, then share your current resume and job description w/ them prior to them being called, so that they have a frame of reference as to what job you are pursuing.

A good reference will reply quickly (same day) to set up a time to talk. If only one of yours hasn't returned your employer's call that means you need new references.