Best wishes - I did a pre-emptive donation to my husband 4 1/2 years ago. We are both doing great. I've read that transplants are most successful if the patient has never been on dialysis, so I'm happy we were able to do it before he needed dialysis (though he got down to very, very low levels of function right before the transplant).
Hope it goes well for you. I found the surgery and recovery easy, but I know not everyone is so lucky.