I don't have direct knowledge, but I have found that it usually take a week to 10-days to get things to most military locations. Certainly, like in Afghanistan, if someone is stuck on a hilltop somewhere, then it takes longer to get to them. The package will arrive "in-country" in a week to 10-days, but then they have to make a special shipment to the hilltop. When it comes to military mail, it travels a lot differently than it does if you were, for example, actually sending a letter or package to someone who lived in Africa the "regular" way. (Also the international postage will eat you alive!)
Hope this helps!
George