3 days in advance is plenty of time ...
@Alan Brown
3 days in advance is plenty of time to discover problems.
What I see is far too many people showing up hopelessly underprepared and then expecting the local IT folk to drop everything to make it work.
True Dat! Working backstage for a fairly well-known conference (Well, El Reg covers it :-), I lost track of how many times the speakers, who were asked to come "on deck" backstage 5-10 minutes before their talk, showed up with "just a few changes to my slides". Yeah, we developed a process for doing these "diving catches", but it was never smooth, or justified.
An then there's the folks who used snazzy custom fonts in the PPT decks, but did not bring the fonts along... (almost as good as the "file:" URLs for images you'd occasionally see on websites. "Hey, it worked on my machine!")