So pass and wait for a sale to occur when you actually have the money. Since you save overall, you only have to go through the pain of waiting just once, hopefully in your youth. After that, your savings on the last purchase (in not paying interest) pays for the next purchase, every time, given the same purchasing habits.
Yeah, except the sale for whatever you buy may expire before "later" comes. You'd save more money purchasing now and paying off the credit card a week or two later in that case. It's not always as simple as you describe.