The largest variables are whether the tartan is in readily available stock or needs to be woven, then where in the queue of the kiltmaker you happen to fall (if their kiltmaker is busy it could be a month or two). The last variable is shipping, more actually customs at the US border, which may hold onto a package for several weeks sometimes, depending on which shipper is used to transport the kilt to the US.

Generally stock tartans can be turned around and shipped in 4-6 weeks typically, faster if you put a rush request (and accompanying charge) on it, then it is again up to shipping to get it to you. Most of mine built from stock took about 8 weeks or so to recieve them from Scotland. You should ask your kiltmaker or an estimated time of completion as well as notification of shipping and tracking information, so you will know preciesely when to start drooling and checking the front stoop every hour in true jones fashion.

Enjoy it when it arrives. Remember to post pictures here, because xmarks rule number 1 is "It didn't happen if there are no pictures!!!"