How long do people have to know you before they can give you a reference? Also should you enclose your proposal with a reference request form?

It is up to you to decide whether or not a person knows you well enough to comment on your academic ability and/or work ethic, and up to the person you ask to decide whether they feel able to help. Remember that you should always ask somebody if they are willing to give you a reference before you name them as a referee on an application.

It would be a good idea to give your referee a copy of your proposal so they can comment on your ability to take on the proposed work. Also, if you have been out of contact with the referee for a while, you could also send them a CV so that they know what you have been up to. Good luck with your application.