I’m wondering if that sounds too long?

This is entirely up to the seller. 

IMO it's normally reasonable for both parties to to allow about a week for collection, unless the listing gives a deadline. Anything much over that and it's wise to message the seller to check before bidding.

Remember that you have to pay through eBay's checkout to get the seller's address and receive the QR code they will need before releasing the item. Cash on collection is not allowed.