Last year an error occurred.
I'd been on holiday in Australia and flew home, arriving at Heathrow at 7 am. Got home by 10 am, sorted myself out by 12, at which point I decided to arrange a punt. Made the booking and turned up at her place at 4 pm; handed over the cash and at that point the jetlag kicked in and I totally failed to get it up. Even had a cold shower, but nothing was doing.
Moral of the story is, wait a day and get over the jetlag before having a punt.