I'm guessing 2 reasons. 1, when they announced the 29 October shipment date they expected to be further along in the process, possibly already at the local logistics partners ready to ship out with a tracking code. Remember that they announced that date relatively early, about a month or so before. Seems there were plenty of small mistakes from a lot of parties here, from people not supplying all documents (or people not requesting all the needed documents) to weekends apparently being a problem even though that should've been known beforehand, to customs being annoying as always.
And because they fully expected to ship on the 29th, they also wanted to satisfy users at the time because plenty were "demanding" a hard ship date.

2, when they realized they wouldn't be able to ship with tracking codes on the 29th, they shifted wording to be "from factory", which is technically still correct. They also kept stringing people along by saying saying the actual shipment was only a couple of days away. These smaller delays are way more digestible, and would keep people decently happy while still being the same actual delay in the end.