If you want one tomorrow, I recommend you get up and get inline at your closest Apple Store at or before 5:00 AM. Hundreds of people who weren't able to get an iPhone ordered for a Launch Day delivery will do exactly that. While Apple Stores "sometimes" have some limited stock for walk-in customers, it is usually very limited and you may well find yourself waiting for hours and still not get the phone you want.
Last year, I had a friend arrive at the Apple Store before 5:00 AM. He waited in line for more than 6 hours and wasn't successful.
You could try other options, such as BestBuy and your cellular provider who may have some limited stock available as well.