Same problem here.
I'm in Belgium, most of my customers are in the US. Etsy won't let them leave a review untill after 3 weeks! Yet my shipping times are 5-12 days.
I've seen a major decrease in the number of reviews I get.
But on the other hand I get a lot of convo's and e-mails about how they love my products (yet were not allowed to leave a review yet).
I know Etsy wants to avoid fake buyers buying products, leaving bad reviews, and then canceling their orders (yes, this used to happen in the past). But this extended period should only be a couple of days, not weeks.
Etsy however disagrees (or doesn't care).