According to Q&A of Journal of Light Construction manufactured hardwood flooring may be kiln dried to 8% moisture content (MC). It recommends the flooring MC should be 3.5 percentage points less than a MC of 11% for the subfloor in the northeast. This information may help to adjust the house relative humidity to an average yearly level indicated by an 11% MC of the subfloor which may be achieved by adjusting the temperature in the house. See the article here. It suggests achieving an average MC of the subfloor maybe as important as acclimating the flooring.