We will be in Haarlem/Amsterdam for a few days in late October and again in early December. When will the Christmas markets appear? Is there a list of there locations that are posted somewhere?
I don’t want to burst your Christmas bubble, but Christmas markets aren’t really a thing in the Netherlands. Yes, there are some exceptions to this, for instance the Christmas market in Valkenburg a village all the way in the most southern part of our country close to the border with Germany. Other than that, we really don’t have a tradition of Christmas markets.
Haarlem does have a Christmas market, but it’s very small and it’s there only for 3 days in mid December.
Amsterdam does have a few squares where they will put up some stalls, an ice rink etc., but it won’t be anything like the Christmas markets in Germany.
More information on the Haarlem Christmas Market can be found here: https://www.visithaarlem.com/en/kerstmarkt/.
I do agree, that it is not comparable with German markets. The Haarlem Christmas Market has been extremely crowded the last few years although last year they optimized the routing making it less cramped.