I want to buy a large item from the warehouse but can't take it until the next day. If I pay for it will they hold it until the next day.

Sorry. I don't know about that.

Per policy they don't have any designated area for prepaid items but guys over the counter are very helpful. You can ask for the favour. You can also place an order online ..

Because Costco does not have designated areas to store large purchase items it is not their practice to hold onto prepaid items. However, it is a consideration only if you get a pre-approval from administrative staff and are able to pick up your purchase at the very start of the day. I believe that to be 10 AM

I have ni idea but call as they're very helpful and you will get a human to talk to