Feedback etiquette

What is everyone's opinion on leaving feedback as a buyer? I won't leave feedback until the seller has left it first because as a buyer and having paid for the item I have completed my end of the bargain first, therefore I beleive the seller should comment after receiving funds which Is before the item is posted. I think when the seller tries to wait they are being defensive and possibly have something to hide or want the opportunity to leave poor feedback if they receive it. When I sell something I always leave feedback first.