I'm nearly always in the front cabin area of J in the 77Ws (international) and have nearly always noticed (when I look that way) the FAs doing the conventional thing in letting Js off before allowing Ys to start disembarking.

One time, in row 6 (and therefore one of the very first off the 77W), I noticed some FAs standing between the exit door area and all of the next-cabin-back pax (presumably including some J) which I thought was a bit odd!