Too many unknown variables to say for sure.
A properly sand blasted surface should be clean enough that you only need to blow it off, and prime it. That is assuming the air supply used to sand blast it was clean enough. If your air supply is not properly filtered to remove oil and other contaminates, then you would need to wash it with a solvent.
Yes, you should etch it before you prime it, unless the primer you use says it is unnecessary, most primers will need the etch for best adhesion.
If it is an air dry primer it should have dried by now, unless he really put it on way too thick. Which would be tough to do, but I have seen it done.
If it is a 2 part primer, it should have hardened after a number of hours at 70 degrees F or greater, regardless of the thickness.
It is possible the product is defective. Or, the wrong type or amount of hardener or solvent was used. Using either too much, or not enough hardener can easily result in improper drying.
If it is not dry soon, I would get a couple spray cans of paint stripper, that should easily remove it. Then, start over.