i was told about a 17 % with FET but as the others say you just don't know. i know of a girl who got preg on first FET and yet i had 5 and did not get any BFP? you just don't know.
i did read the other day in this IVF and conception book at a book store that stress plays a big part in it and that stressed mums have less chance of a BFP. who knows

good luck and hope for that BFP soon