If you want the flooring to be stable and remove most of the chance of it cupping you must wait until the HVAC is on and running. In my experience it needs to acclimate in a conditioned house for 3-4 weeks.

Is this getting sanded and finished or is it prefinish?
3-4 weeks is a little much but to each his own.

Biggest thing is making sure the mositure in the subfloor matches or is really close to that of the flooring.

But it is important to make sure your home has an established environmental condition before installing.

thank you, gamountains. You have synthesized what I've been reading - essentially the subfloors and finish flooring have to be equalized to more or less what they will be when we're living there, 12 months of the year. We are in Putnam County, NY, about 50 miles north of the city but with much higher altitude so it could be as much as 10 degrees colder in the winter and maybe 5 degrees cooler in the summer BUT on a lake in a valley and there's a lot more humidity (or so it seems). With the nice breezes we didn't plan to use the A/C very much except to dehumidify when necessary. We have now brought the house down to about 40% RH using dehumidfiers. No one has checked the MC of either the subfloors or the oak that is already on-site but not installed. In addition, there are Viega radiant heat panels on top of the plywood subfloor so they add a third level to check. I have told the contractor not to install the floors until the A/C is in and running and the house is between 55 and 65% RH (which I think is a reasonable average, although we might let it rise higher in the interest of energy conservation and liking fresh air) and the flooring is sitting there for at least 10 days under those conditions. I realize that violates what most have said - 2-3 weeks, but I am operating on the premise that if the R&Q swells after installation, it can be corrected to some extent during final sanding and finishing. Also, my architect says 7-10 days and he's not about to stand up to the contractor he recommended. There will be irregularities in the floor, and I will have to live with that, but given that I don't want my contractor to walk off the job when we're so close to the end, I have to draw the battle lines someplace. The bigger battle right now is over how to get the A/C installed. Please correct me if you see anything that doesn't seem reasonable - can't go for perfection at this point - reasonable compromise is the name of the game now. Thanks.

thank you, gamountains. You have synthesized what I've been reading - essentially the subfloors and finish flooring have to be equalized to more or less what they will be when we're living there, 12 months of the year. We are in Putnam County, NY, about 50 miles north of the city but with much higher altitude so it could be as much as 10 degrees colder in the winter and maybe 5 degrees cooler in the summer BUT on a lake in a valley and there's a lot more humidity (or so it seems). With the nice breezes we didn't plan to use the A/C very much except to dehumidify when necessary. We have now brought the house down to about 40% RH using dehumidfiers. No one has checked the MC of either the subfloors or the oak that is already on-site but not installed. In addition, there are Viega radiant heat panels on top of the plywood subfloor so they add a third level to check. I have told the contractor not to install the floors until the A/C is in and running and the house is between 55 and 65% RH (which I think is a reasonable average, although we might let it rise higher in the interest of energy conservation and liking fresh air) and the flooring is sitting there for at least 10 days under those conditions. I realize that violates what most have said - 2-3 weeks, but I am operating on the premise that if the R&Q swells after installation, it can be corrected to some extent during final sanding and finishing. Also, my architect says 7-10 days and he's not about to stand up to the contractor he recommended. There will be irregularities in the floor, and I will have to live with that, but given that I don't want my contractor to walk off the job when we're so close to the end, I have to draw the battle lines someplace. The bigger battle right now is over how to get the A/C installed. Please correct me if you see anything that doesn't seem reasonable - can't go for perfection at this point - reasonable compromise is the name of the game now. Thanks.

I don't see that much of a concern providing the moisture levels are in a safe range for the floor and subfloor. R&Q will expand the way the growth rings are positioned in the product itself. In this case vertically, that essentially eliminates most problems with wood floors; gaps, cupping and buckling.

I wish I knew more about radiant heat systems, but one thing is clear when they are planned for use; crank them up very gradually. Nothing in nature likes to be shocked and that includes hardwood flooring.