The Fashion Shop boutique associated with the new Fashion Week adventure currently shows a countdown timer of 6 days, 16 hours, and 30 minutes remaining... which will roughly coincide with the end of the current quest.

Typically, we get an additional four days (or so) to do extra shopping before the quest stores close... so I think this is a bug?

As an afterthought, I just checked the NEWS post, which shows a closing date of Sunday, September 29th at midnight... so definitely a bug (maybe :P)!