Between the end of Act One and the beginning of Act Two, eight days go by. Clearly a great deal happens during this gap because the accusations of witchcraft go from being a relatively private affair—taking place within the home of the minister, the Reverend Parris—to a very public affair, with a bona fide court headed up by various magistrates and the deputy governor of the Massachusetts Bay Colony.

You could write quite a bit here, including a description of the arrival of Deputy Governor Danforth and his introduction to the Reverend Parris (who is so keen to be on the man's good side, as we see in Act Three). You could also write about the involvement of Mr. Hale in setting up the court and parsing through the accusations (especially since he, in Act Four, reveals how responsible he feels for all that happens to the innocent who are convicted). You could even write about how and why Danforth and the other magistrates decide that it is the "voice of Heaven . . . speaking through" the girls who make all the accusations. By assessing the personality traits revealed in the later acts, you can show how these characters got their start in Salem.

In order to effectively insert a gap in the action, a type of break where presumably other elements can be introduced, one has to find a location in the drama where time passes.  The gap can be inserted at such a point.  Interestingly enough, Miller himself had inserted a gap between the end of Act II and the start of Act III.  This gap featured Proctor meeting up with Abigail late at night, as a last opportunity for both to confront one another before their inevitable confrontation in the trial.  It is interesting to see this as a potential point where a gap can be inserted. Both still display their emotional ferocity, but it is one in which there is a calm before the storm of the trial hits both.  

This same approach can be used with inserting a gap between Act III and Act IV.  A gap can be inserted at this point through another meeting between Proctor and Abigail.  It would be interesting to insert a gap where both meet now that both have endured the impact of a trial.  Proctor is in jail.  Abigail must flee. Both could interact with one another one last time, the result of both lives being changed by the trials.  This might be a location in which a gap could be inserted because it would represent a highly charged and emotional moment before the further emotional ignition of the final act is to take place.