Well your question depends on different situations. Your MOS, the unit you will be joining and even what is happening in the world.
If your MOS is in combat arms such as infantry, artillery, recon, etc then you may deploy sooner than later, also intel, linguist, deploy a lot as well. Supply, admin, cook, Motor T, may not deploy as much but then if the unit you will join deploys a lot then any MOS becomes deployable.
The currrent situation in the world also dictates what may happen. Now the Marines are leaving IRAQ and going to Afghanistan so if the president says I want more Marines in Afghanistan then your unit may be one of them so as you can see it depends on certain things.
Hope that helps