I don’t think Hamlet’s given them their full half hour call here. I mean, there’s pretty much only a page before the audience shows up to see this show. So maybe the players are already made-up and dressed. Hopefully, they got whatever warm-up they needed in before their pre-show meeting with the Prince of Denmark.
Maybe making themselves ready at this point is just some grounding, centering, about to hit the stage stuff. Some last minute props checking, etc. Maybe getting ready means PLACES (And squeezing in some clown reprimands.)