Another thing we might want to keep in mind here...
I get quoted for x amount of BTC, and I have until 6 p.m. to deposit the money.
At 4:30, I go, deposit the money while I'm running various errands. I get home at 7 to find that my order has been released to someone else because I didn't provide proof of purchase in the allotted time frame. Now I have no BTC and no way to get a refund. In addition, the seller got a double deposit - what then?
All of this is purely theoretical, and food for thought.
You do not have until 6:00 to make the deposit. You have until 6:00pm to make the deposit and reply back to the support thread with your deposit slip.
Plus when you get quoted the price, the bitcoins are placed on hold and will not be sold to anybody else that day.