I was actually surprised recently when a seller left feedback for me before the item arrived. Every other seller I've purchased from (but two) have left feedback only after I left it when I received the item. The two that didn't never left feedback at all.

With one exception, I've paid the day the auction ended. In a few cases, I paid within minutes of it ending. The one exception was an item I didn't think I'd win, so I didn't pay attention to it. I did pay within 3 days, though.