Homeowners take on a responsibility for keeping the temp and RH within a certain range so the wood can give you good service and life. How you do that is up to you either by the HVAC system or a humidifier/dehumidifier or opening/shutting windows, ect. It doesn't matter how you get there as long as you arrive.
Acclimation is not determined by time, but rather through using a moisture meter. You are checking to see if the flooring and substrate moisture levels are within a certain allowable range... equalization may be a better term for this. You want any needed corrections to occur before the wood is cut and fastened down.