There won't ever be a 'last' photon. It might take 1 year for the next photon to be emitted once it's ALMOST fallen in, then 100 years for the next, then 10,000 years for the next, then a million years etc but there can't be a last photon. Like there's no last prime number. Until the black hole evaporates and whatever was falling in isn't falling in any more which is very odd if the thing from its perspective ACTUALLY DID fall in.