CO2 for Kegging?

I have a carboy of wheat beer that I want to keg. I have all the equipment, but my CO2 tank is empty. Do I need to hook it up to pressurize the keg after I fill it, or can I just put in priming sugar, add the beer, and seal it up? I'd like to get it kegged today, but the LHBS is closed, so I can't get my tank filled. My next chance to do it will be Wednesday, when I plan to brew as well, but I'd rather get it done today and not have as much stuff to do all at once later. Thoughts?

If you plan on naturally carbing your beer then you can add the priming sugar and seal it up(however kegs aren't usually sealed till some pressure is applied to them). However, you are going to have to wait at least a couple weeks for it to carb. Why don't you just wait till Wednesday and then you can force carb it and have it ready alot quicker?

Well, I don't mind waiting for it to carb. I have plenty of other stuff going on. But, I could seal it without pressure, right? So I could put it in the keg without priming sugar today, then put the CO2 on in a few days?

As ExpertBrewers pointed out kegs don't seal well until pressurized. I would leave it be until you fill your CO2 tank then force carbonate it as you won't be sure it will prime properly if it isn't sealed.

GT

Your brew can sit in the keg either way. If you lube the o-ring, you can probably get it to seat without CO2. Even if it doesn't seal, you can always force carb later.