agreed on the 35-40min(ish) window at LHR to JFK.

i usually get to the gate at 25mins out and by then the fast track queue is empty so i can breeze right on to the plane and by then the J and F cabins are usually settled. so far this summer, i have not yet had a full J cabin on my last 8 or so flights since june 1 so if you want to queue with the rest of fast track, arrive 35mins ahead. if you want to avoid lines, try ten mins later