You should not wax first. I think you may be a little confused. Wax is only used before gelcote if you are gelcoting against a mould. It keeps the gelcote from bonding to the mould as a release agent. In this case, you want the gelcote to bond. In addition, a wax can be added to the gelcote mix that will allow the gelcote to fully harden. Otherwise it will remain tacky. This wax moves to the surface to keep the air away to allow the hardening, but does not reduce the bonding of the gelcote to the ski. You must sand the surface of the gelcote to remove this wax if you want to apply a second coat.