Disclaimer: This blog is for speculation exclusively. All theories are mostly mine, which is to say they are composites of several theories I've read plus a bit of my own speculation.
One of the details that has bothered me for many years is: what happened on October 31, 1981 after Voldemort attempted to kill Harry? When you think about it, we're actually never told clearly what happened for the next 24 hours, just bits and pieces. In this blog I shall expose most of my insane ramblings plus some details callously ripped from other theories.
Firstly: how was the second floor of the Potter cottage blown hallfway open? Some guys already discussed something that really struck out to me: we are accustomed to seeing what happens when the Killing Curse strikes a living being (insta-kill) or an inanimate object (green flaming explosion). But we never truly clarified what happened after Voldemort proclaimed "Avada Kedavra!" and "he broke". Some one already mentioned (and I really liked that theory, whoever you are) that it's highly possible that when the Curse struck Harry on the forehead (leaving the distinct lightning-bolt scar) the Curse didn't just rebound like when you shine a laser pointer against a mirror and the beam trails off in a straight line. No, I believe it's more likely that Lily's sacrificial barrier somehow destabilized the Curse, causing it to rebound everywhere similar to an explosion, which would explain how Voldemort's body was "destroyed", instead of his soul merely being ripped from his body.
And now, the main event: what happened after the blast? A few details we know: we know Hagrid was there, since he personally extracted Harry from the rubble. We know Wormtail also dropped by undetected and salvaged Voldmeort's wand. We also know Sirius was briefly on the scene, since it was at the cottage where Sirius lent Hagrid his flying motorbike. We also know from the very first chapter of PS that it was at least a full 24 hours before Harry got from Godric's Hollow to Privet Drive. We know for a fact Sirius was the first at the scene, followed closely by Hagrid. I'm thinking it was around the same time that Wormtail got there and rescued Voldemort's wand. I think that amidst the chaos, Sirius and Hagrid overlooked it or mistook it with a mere piece of rubble. It's likely that after Hagrid extracted Harry and took the motorbike he spent the next 24 hours travelling England to make sure that no Death Eaters were tailing them, to keep Harry's location secret. For all we know, it's possible Dumbledore himself gave the order to keep Harry in motion for at least one day, while he made the necessary preparations to cement the blood bond charm that would protect Harry for the next sixteen years. It has also never been completely specified, but judging from Sirius's dialogues I think he tracked down Wormtail that same day, thus placing the massacre of the twelve Muggles on Novemver 1.
Other disclaimer: Since this is a theory blog, this is not even its final form; it is extremely possible that I may someday revisit it and add further notes.