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.