I think it might be a NOC/SS thing, just by going on what Punk said in a recent interview about it being on or after Summerslam. NOC is my guess if it's finished, since it makes sense within the context of the PPV (being about champions and all).
Of course, if Cena is going to walk out as champion at NOC, then it could take as long until the Rumble for the new belt to debut. I mean why would Cena just dump the belt he's been long associated with? (which actually is his, if you recall, in the storyline Cena commissioned a new title belt that "suited his character" shortly after he won the title for the first time.) The way I see it:
This belt (it will be referred to as "title" since Vince is weird about them being referred to as belts) represents everything that is wrong with the WWE - namely John Cena. The only way that I, yes I the actual WWE Champion can hope to break away from that association is to dump this piece of crap. And as champion, I demand that the WWE board of directors selects something with class, that doesn't feature anything that disrespects the WWE Championship, it's lineage and most importantly - me.
If they want to give Punk heat, they could have him destroy of deface one of the replicas, or throw the belt away as rubbish. The new title would then be unveiled at NOC and presented to the winner of the match.