I am waiting to get a kidney transplant. when should i tell the person who's interested in me?

Now: Since you are waiting for a kidney transplant, you must have signifcant renal damage. This damage can lead to may medical issues that you will have to face prior to a renal transplant. Thus you should have the full support of the person who is interested in you. So, this individual should be aware of your medical problems so the can plan acordingly as well.

Any time is good.: If you are asking about someone who may donate a kidney to you; you should openly discuss this once you are medically and psychologically ready for transplant. Be open and optimistic, you will be surprised that many of your friends or relatives will be happy to help and were waiting for you to ask.

A personal decision: I think it is a personal decision one has to make. There is no doubt that the person will eventually find out. What you might want to consider is factors such as your need for dialysis, and waiting time for kidney transplant.