I rushed a few weeks ago when temps were FREEZING. I arrived somewhere in the area of 7:15 and there were already a bunch of people ahead of me. They no longer hold the front two rows for rush: they sell what's left over. (I got box seats.) People seem to love the show, so I'd definitely get there at 8:00 at the absolute latest.
Just rushed Godot on Sunday, January 5; got in line at 10:00 for the box office opening at 12:00 and there was already a good dozen or so people ahead of me. By the time the box office opened, there were nearly 60 people in line. I was with a group of friends and I asked for four seats together, so he sold us one of the boxes. Had I asked for only one or two, I think I may have had first or second row seats (the person directly in front of me got a second-row seat). I'm not sure how many tickets they sold in total, but I would definitely say get there no later than 10:30!
Thanks for all your info! I rushed on Saturday and got there around 7:15 am and was first in line. The temperature was absolutely unbearable, but it was all worth it in the end. Got front row seats!