Just spoke to my dealer (Grange, Barnet, N.London, who have been fantastic, by the way) on an unrelated matter, but asked him about XE-S's, and if he'd heard anything. He said that they are quoting January on new orders, but that they are taking delivery of previously ordered XE-S's in the coming weeks, so I suspect that it may be a combination of factors that may cause an individual order to be delayed.
My dealer confirmed, for example, that my order had been upgraded to 10-way electric seats as Jaguar had a supply issue with the 8-way. My order itself has been delayed until September due to issues (I believe related to supply, not quality) with the HUD unit.
Working for a software company serving the manufacturing industry I know that it is not easy juggling a supply chain of that complexity, although it does not make the wait any more bearable...