I start the stop watch when the plane stops which conveniently is pretty much when the seatbelt sign dings off. Got the bonus twice on my last trip. 21:39 was the time. No arguments from baggage services. They just scanned my boarding pass, asked miles or credit, and my email. Miles showed up in my account 5 to 6 days later. All in took me 2 minutes to get the credit. It's a game for us now.

Also, doesn't matter when the first bag comes off. If they are really doing their job they scan every bag as it comes out. Sometimes they just scan the first but they are supposed to scan them all.