I can't speak for the upcoming holidays, but yes they generally shut down then (in past years). But they wouldn't have scheduled anything then, so they shouldn't be pushing dates back because of it.
The only reason I know of that would be affecting dates is this aluminum shortage they're dealing with (the fire at the hot mill). Aside from the RHO, 100% of the current production trucks at SHAP are being built with steel hoods now. And I wonder how many other panels are in short supply due to this.