Hi sdmat,
There is more about the break in and adjustment period in post #3 here. It can vary from person to person but it would normally be about a month or less (sometimes much less if the mattress is similar to what you are used to sleeping on). There are also some suggestions in post #2 here that may also be helpful.
While it’s not always possible to to track down temperature regulation issues for any particular person on a specific mattress because there are so many variables involved (including your room temperature and humidity, your sheets and bedding and bedclothes, your mattress protector or any mattress pads you are using, and where you are in the “oven to iceberg” range) and some people can sleep warmer on mattresses that most people are generally fine with … there is more about tracking down a potential cause or causes for temperature regulation issues (at least to the degree possible for a specific mattress) in post #2 here and the posts it links to that may be helpful.
Phoenix