My Daughters actually did something like that (i dont but they are better than i am with these things and are professional online shoppers lol)they obviously allocate the actual sale once the CC payment is completed, rather than holding the position while it's in your cart... In this case the only way to ensure you'll get it done quickly enough is to setup something to auto-fill your credit card details so it only takes a few seconds instead of a close to a minute to fill it out.
Just seemed like it didnt work how it was meant to. I managed to get them in 17 & 19 but this year was not the same