When is the best time to post an online review of a product you purchased?

When you purchase a product then review it online, how long do you wait until posting a review? Also, do they normally let you update your reviews (like if something breaks after six months)? Obviously this isn’t something I normally do myself, although I will often read reviews to get an idea of other purchasers’ opinions. Just curious how other people do this.

If I review it at all, I’ll usually do it within a few weeks of purchasing it…unless there’s something obviously wrong with it.

I buy on Etsy fairly often, and they don’t allow you to review an item until after a specific amount of time. A week at least after it’s delivered or shipped…can’t remember.