By definition, the acclimation of hardwood floors occurs at a point when the installation space and the hardwood flooring have reached a moisture equilibrium. Simply put, equilibrium has been reached when the hardwood floor and space are no longer trading moisture to balance each other out.
A particular strategy in acclimation is becoming more common, and needs to be addressed in order to avoid customer complaints. Tearing the box ends off of hardwood flooring cartons is not a proper way to acclimate a floor. In fact, this process can lead to a failed installation. (pictured below)
Hardwood does not release or accept moisture uniformly across a board. Tearing the box ends off as a method of acclimation only allows moisture migration at the point of the box opening. The resulting moisture migration at only the box opening can lead to complaints of "miss-milling", and can make installation difficult or even impossible.
If an installer is tearing box ends off as a method of installation, ask them to stop this immediately. Manufacturers that see this will not accept a miss-milling complaint, because it is very clear that the product wasn't acclimated properly. You may be on the hook for this flooring if this is how acclimation is being done.
If you get a complaint about how anywhere from 20-35 percent of the boards "aren't going together well", then have a look at the boxes. You may find that the acclimation caused the issue.
A better acclimation habit would be to simply leave the cartons intact, and rest that hardwood in the installation space as long as temperature and relative humidity controls are in place as recommended by the flooring's manufacturer.