It’s been a long time, but I’ve done the trifecta more than once. There is a class 3 way down the south face of Russell. I’ve only climbed the north face of Whitney once. The route I found was crap, though there may be better routes than mine. After Russell, I would just go up the Mountaineers’ Route to Whitney. The fastest way is to trot down the trail to Muir and then hike back up to Whitney. From there, you can downclimb the Mountaineers’ Route, which should be faster than the main trail.