Polonius gets his "enter" instruction later, after line 042.  However, that is a playscript entry, to ensure the Polonius actor is in correct position to participate in the dialogue.  To be in correct position at that point, Polonius must arrive on stage earlier.  Polonius's "stage entry" is earlier than his playscript entry.

Polonius gets his "enter" instruction later, after line 042.  However, that is a playscript entry, to ensure the Polonius actor is in correct position to participate in the dialogue.  To be in correct position at that point, Polonius must arrive on stage earlier.  Polonius's "stage entry" is earlier than his playscript entry.

Shakespeare wrote the playscript in a way to ensure it would work for the dialogue, to put characters in the right position for the speeches.  The exact timing of a character's presence onstage is a somewhat different issue, although dialogue presence does require stage presence (with the rare, peculiar exception such as the Ghost underneath the stage.) The timing of a character's stage presence is something for the director's notes, which we unfortunately do not have for ''Hamlet.''  Fortunately, knowing that Shakespeare included visual cueing lines in ''Hamlet,'' the timing of physical stage presence can be reconstructed.  One looks for lines that go along with an obvious action, in the area of the dialogue that is shortly before the playscript entry is printed.  One also takes into account what a character must hear, to justify any line he says later.

Shakespeare wrote the playscript in a way to ensure it would work for the dialogue, to put characters in the right position for the speeches.  The exact timing of a character's presence onstage is a somewhat different issue, although dialogue presence does require stage presence (with the rare, peculiar exception such as the Ghost underneath the stage.)