Nekolover_8
I would have to agree with the notion that all horcruxes were made by this time. We are also forgetting that Neville Longbottom was born on July 31st as well. Maybe he and Voldemort are the ones in the prophecy. I mean, Voldemort never actually heard the whole prophecy before killing James and Lily Potter.
Now, this is an interesting point, however, it doesn't quite work. See, we
do hear the whole prophecy, which is why it is certain that it is Harry. Voldemort marked him as an equal when he foolishly tried to kill him, and he gave him 'powers the Dark Lord knows not'... He made Harry the one named in the prophecy by his own folly.
Oh, and about the locket. You know how, in the fifth book when they were clearing out Grimwald Place, they found a heavy locket that wouldn't open? I think that was Slytherin's locket/Horcrux, and so do my friends. Also, RAB is Regulus Black, I think. He did say he knew he would be dead by the time Voldemort found the fake, but he never got the chance to destroy the real Horcrux, which would explain its presence at Grimwald place.