My local Jaguar dealership told me that he has 6 pre-orders of I-Pace, and there are only three dealers in Arizona, which is not a big market. Let us assume that there are 250 JLR dealerships in total (The only count I found was that they had about 292 dealerships in 2012 and were going to reduce it by 20%. If they brought it down to 225, and they have added a few after that as they have in Phoenix let us say they are at 250 dealerships. Let us assume each has an average of five pre-orders that get converted into sales. So in theory they have a back log of about 1250 cars that they can sell in the first month.
Now there are many ifs, the first being they actually land enough supplies in the US by the first or second week of November. Not sure if JLR has enough inventory to do this. Then there are conversion into sales parameters. Arizona is not a representative market for JLR (the second Phoenix area dealership started less than a year ago). I am making a conservative assumption of 6 back-orders based on talking to one dealership. Further, there may be more than 250 dealerships slightly skewing the calculations. However I would guess then can sell at least 1200 cars in the first month, if they have inventory. Difficult to judge if they can continue that pace beyond the first month or two.
However, given that Jaguar sold only about 40,000 cars in the US in 2017, even if they sell about 8,000 I-Paces in year (assuming these are buyers who would not have bought another JLR product i.e. cannibalized their own sales by buying the I-Pace instead of the F-Pace), their volumes have gone up by 20%. But the caveat is that there are too many ifs. It will be around 2Q of 2019 before we know if I-Pace is a serious competitor to the S/X.