Management has never "asked" me to do it on the first rehearsal, but I always do it then when we are doing all the other votes for 6-hours days, breaks, etc. I personally like getting it out on the table at the beginning of the process.
I have never been asked to vote on it later, I generally get "it's fine to do it, I just don't want to know when it is happening" response. I do, however hold off on the signing of the rider until we move on-stage. It acts as a gentle reminder that it is about to happen, and that they should voice any concerns now.