Coming from a background making consumer electronics in China (basically what you're doing - possibly of similar part count, higher volume) - this response is reasonable. Shit factories exist everyone on the planet - as do quality ones (including China). You pay for quality and you manage for quality (don't forget the latter part).

One exception. A ship date of November means a mass production build in October. An MP build in October necessitates a production verification build in September and at least one design verification build in August.

Generally, once your tooling is DFM ready, you need to give yourself 2 months to have tooling made (as fast as 4 weeks to T0 first articles) and then another 4 weeks for revisions/fixes and finalization. That means DFM compete by the end of May and a design hand-off basically today (but no later than the end of the month).

You can cut some corners to save time by skipping the production verification build. The whole intent is to get quality management in order to raise yields (lower cost) - you can't have SOPs in place until after your first build. So if your second build is a mass production run - you're using un-tested SOPs (SOP error is potentially multiplied by the build size) or SOPs without operator feedback (good way to get noncompliance which is worse than a bad SOP). That has burned me in the past, but wouldn't necessarily stop me from proceeding in that way (depends on design stability)

I don't know what phase you're in - but November would be a zero slip, zero test response schedule assuming you've got a master services agreement in place with a supplier that's ready to receive the initial hand off. I imagine an X-mas delivery is the internal slip goal - doable so long as everything is going right.

Disclosure: I backed your project. I think its neat and at such a low price (even with $70 BOM), I think you're going to need a ton of backers to reach stability. NPIs take gobs and gobs of money. Also, I hope this post is received positively - nothing here was written with ill will or with skepticism, as I said, your post was reasonable and the schedule technically possible.

All that said, I'd be happy to answer any questions/advise if you're feeling short (here or privately, I'd send credentials privately if you'd like). Otherwise, best of luck (and I hope you like real Chinese food, tasty)