ask your registrar for any help, that's their 800 number in action. Also, consider if you are selling domains out of a godaddy account, it is simple to 'push' the domain to a new buyer if they also use godaddy. So tell your buyer it will cut 7 to 10 business days off the transfer time, and to let you know when they have set up their 'free' godaddy account and to give you their particulars. There is an excellent tutorial on the godaddy site on how to do this between their accounts. it's the easiest way, so go for it.