If you're clumsy enough then yeah buy it ASAP. For most people you should be fine to hold off and get the most out of it. If it's cheaper on Barclays then I suppose that is worth doing at time of purchase. What's the price difference?No because what’s stopping you from damaging the iPhone in the 60 days? Also AppleCare is discounted when taking out the 0% Barclays finance.