zx32tt:
I hope you have an air-conditioned shop.
Pro-bond (polyurethane adhesives in general) reacts with moisture to harden. The reaction rate is also speeded up by temperature. Here in FL, which is almost as hot, & humid as Houston, polyurethane glues set up pretty fast this time of year. I also notice that the polyethylene bottles that the stuff comes in allow some diffusion of water vapor. After a while on the shelf, there's a lining of cured adhesive on the inside of the bottle. Squeeze the bottle, hear the crunch.

I digress. My point is, if you are going to sheet a foam-cored airfoil, store the components in an air-conditioned area so you will have adequate working time. If everything is pre-heated and clammy, you may not get it assembled before it begins to cure.