Prime in keg

I plan on kegging my brew but not tapping it for a few weeks. Can I use priming sugar when I keg it so I don't have to wait for it to carbonate when I tap it? Also, how long can I leave beer in a keg before I tap it (primed or unprimed)?
Thanks

Two reasons to wait. One is to carbonate, the other is to condition it. The first takes less time than the second.

Priming with sugar takes more time than priming under C02 presure.
You don't have to wait until tapping to carbonate. Do it as soon as you keg it.
Depending on the beer you can leave it 6 to 12 months maybe longer.

I don't think I'm quite getting the process here. So I keg it w/o priming, pump some co2 in, and just let it sit that way? I haven't kegged any yet, could you give me the play by play on the process so I dont screw up my first batch please?

Go ahead and prime it, since you are planning on waiting (good policy that). For most ales, 2-4 months out would be best for flavor. More, if you keep it cold.

When I keg, I put a little CO2 on the keg to be certain the lid is seated. Whether or not I prime depends. If it was a kit & there's priming sugar, I toss it in. If not, I force carbonate when I put it on tap. Typically, I age ales for 4 months, but as you can see in my sig, some of them are much older.

If you decide to prime, burp the keg before connecting to the CO2. It won't hurt the carbonation, but it will prevent backflow into the regulator.

Two methods.

Priming with DME/Malt/Sugar

Add beer to keg with appropriate amount of primer. let sit for 2-4 weeks at room temperature. It should then be carbonated. You just need to keep C02 pressure on after serving a couple of pints.

Force carbing.

Add beer to keg. Pressurise and leave or Pressurise and shake. Chilling helps. I think it takes up to a couple of days. (I don't use this method)
Good reading - http://www.defalcos.com/draftbeerinfo.htm

Thanks, that was exacally the info I was looking for. I also enjoyed the read about it on the Defalco's web site. I didn't know they had such good stuff on their site, Defalco's is the local brew shop where I got my set-up and supplies.