Heh, on the other hand the one and only time I arrived hours earlier was in the US :) I was flying AMS to SFO via Portland, we cleared immigration unusually fast, and when I got to my gate (connecting flight was in like 4 hours) the lady there asked if I wanted to move to an earlier one, boarding in ~20 mins. I said sure, and I even got the checked-in luggage at SFO (she did say that there was a chance it'd get sent later).

Airlines are often happy to do this as the earlier flight is likely not full, and allowing you on it costs them nothing while it opens a seat on the later flight which they can then sell to a standby passenger.