stephimarie said: "as of June 23 the first person in line was 5am. But that's for all cancellation tickets so you'd probably be good getting there later than that for sro."
Though, as mentioned, there are very much fewer less-expensive SRO's than the more-expensive seats, with sometimes even zero offered, and often people at or near the front of the line are like-you SRO-only people so you might not necessarily want to chance being further back. You will, however, have to wait until near, or sometimes AFTER, curtain to even find out if any SRO tickets will be made available to you even if you're the very first person in line.