I always pay straight away because if I’m bidding on something it’s because I want it, and It also gives you good feedback, I don’t like to keep people waiting for their money, there has been a few occasions where I put a bid in early days and forgot about the item, and I won it , but eBay send you so many notifications to pay on the app and on your email, most people have the app on their phone too, so there’s no excuse really not to pay