Here is my standard procedure.
As a seller, I leave feedback for the buyer as soon as I get paid. If the buyer does not leave feedback, that is OK with me, it is their choice.
As a buyer, I leave feedback when I receive my item and have a chance to look at it. I don't care if the seller has left feedback for me or not. That is their choice to make.
I don't really care about feedback but care more if I satisfied the buyer (no feedback to me is good feedback), and from the other side if the seller satisfied me or not.
This feedback issue has been discussed many times on the
ebay boards, some care and some don't, and some take it to extremes from both sides.
My system works for me, is easy to implement and very straight forward.
As I said before, what works for me may not work for others and vice versa.
I do believe however, as a buyer I would rather have a great item than feedback and as a seller, I would rather have the buyer be happy than be concerned about feedback