We are facing the same problem. Our screed is now 6 days old and we ventilate daily. We are currently waiting for the electricity for our underfloor heating so that we can run the screed program in at least 1 week.
so, after consulting with the site manager, we ventilate 1-2 times daily for 10 minutes
at the end of next week, beginning of week 49, the heating installation will be done (central, no underfloor heating)
and then heating can start - then it should become easier.
dehumidifiers, says the site manager, we would not need (but I’ll keep that in mind)
We had our house set up at the beginning of December last year. Without underfloor heating. The heating was turned on after pouring the anhydrite screed and heated to about 30 degrees. A window was tilted open for ventilation, and there was an exhaust fan at the top. Meanwhile, almost always someone was in the house working, which left only 3 weeks for aeration. After 8 weeks, the residual moisture in the screed measured by CM was 0.2%, so almost ready for covering. In total, about €600 worth of gas was used for heating.
Per cm of cement screed one week, it is said - under optimal conditions. This morning the house had 92%!!! humidity, after airing on a sunny day 67%. I wish you luck