I concede the point about getting the guns into his room, but I stand by my other point about premeditation. The lunatic planned this.
Well, yeah... I'm not sure how far in advance, but it could have been as little as a couple days. True, in Vegas it can be hard to get a room only a day or two in advance but it can be done, especially if you don't mind paying for a suite (no idea if his was, just going on the rumor that it may have been).
I guess we'll find out more, like just how far in advance he got the room, because that right there tells us a lot of about just when he started planning, or at least going into the operational phase. That and "where did the guns come from, and how long ago".