Even though auction listings see the most bidding activity toward the end of the auction, they tend to pick up a certain number of watchers at the beginning from buyers searching by "newly listed". If your auction doesn't show up until late at night, you've lost the prime exposure time for this. By the following evening, when most people are looking again, you are no longer a new listing, but are probably buried in the mix. So yes, the 6 hour delay can indeed hurt an auction style listing. Fewer watchers means fewer potential bidders, and thus lower prices on average. BIN's are even more impacted due to the nature of the buying process.