AW has been very clear about why 102% was incorporated into the design. It is to allow for that extra 2% to be used during rejected take-offs and OEI landings to remain within the min of 90% Nr for OEI landings. It has nothing at all what to do with climb performance, so using it beyond Vtoss has no benefit.
In my opinion waiting until Vy only increases the chance of crews exceeding the 90 knot limitation.