I tend to give my buyers up to 5 or 6 days, then I send a friendly reminder message, wait 2 days, then file the Unpaid Item Case.
Of course, the length of time I wait for payment in any given transaction depends on several factors. The above is not a hard and fast rule with me. For example, if the item is an expensive garment (say $200-300), I figure the buyer will have had time to consider the purchase, and should be ready to pay within a few days at most.
The main issue for me is having an expensive and sought-after item sitting in limbo, unable to be relisted, while I wait for payment.
Contact is my other criteria when deciding how long to give a buyer to pay. If a buyer actually contacts meI will usually give them any reasonable time to pay -- sometimes up to 2 weeks or more.
You have to balance the payment time against how important it is for you to be able to quickly relist the item, or get paid, and how much time you'll have left to process an UID. You don't want to leave things until beyond about a month in any event, as you don't want to get too close to the limit for filing an UID.
