How long after purchase can you rely on Ebay's money back guarantee to prevent scams?

I bought an item from a seller account created on the same day as the listing with one review. After checkout, the payment didn't go through immediately and was pending, I sent a message to the seller about this and didn't receive a response. The payment was processed after waiting a while, and I received a message from the seller saying that the item has been shipped and that it should take 3-4 weeks to arrive (average 25 days), and that he's going to travel.

From what I've read, Ebay with-holds funds from new sellers for 21 days, so if it takes me longer than that to know that I've been scammed, would it be possible for the seller to clean out the paypal account beforehand?

edit: the product page listed estimated delivery as 9-15 days, on the purchase history page it's Nov 20 (24 days) at the latest.