Well, for the benefit of others - I called customer service just now, asked a few questions, added a couple of items to my order - and was told the lead time for shipping an order like this is about a week. No long phone wait, and the rep was courteous, knowledgeable - helpful.
Therefore, worst case would put my order at arriving - no later than about the 22nd, which is a few days before I "need" it. I'd like to finish my project a few days before the next gun show happens at the end of the month.
It will essentially be an extra AR, mainly for .22 use - but will also have a new BCG (that and charging handle just added to order) if I want to use it for 5.56 as well.
If I find problems arise, with what has so far been a simple deal, I'll post the details.