I'd give it a week. Some people go on vacation, get tied up on something. A week covers long weekend trip.
After a week has gone by, and you have sent him an invoice and contacted him through enays contact buyer (through auction page), then file a non-paying response. Ebay will then get into it. If he doesn't respond, you will get your relist fees.
I always give people the benefit of the doubt and try not to leave negatives. Som people like to leave a neg if not responded to in 48 hours.
I had a negative left that has now scarred my perfect 100% rating, and it cant be removed...really sux when it wasn't my fault.
Good luck to you.
rocndave on ebay.