What is the term shouted by stage management to signal that it's time for actors to come onto the stage for the first scene?

The correct term used by stage management to signal that it's time for actors to come onto the stage for the first scene is "places." While the term you indicated is "Begin," the more universally recognized signal in professional theatre is often when stage management calls for actors to take their designated positions by using the term "places." This helps ensure that everything is set for the performance to start smoothly.

The other options tend to be either related to different cues or not standard terminology in this context. For example, "act call" typically refers to a notification that a certain act is about to begin, rather than specifically signaling actors to enter the stage. "Beginners" usually refers to novice performers or people new to acting and does not serve as a cue. "On stage," while somewhat related, is not the standard term for calling actors to their positions for the start of a scene.

Understanding the correct terminology is essential for effective communication in theatre, which often relies on precise cues to maintain the flow of a performance.