Portia is first mentioned in act one scene one, by Bassanio as being beautiful and sought after. Antonio says he will help Bassanio win her affections. Two forwards are set up here, one in that the audience wants to see Portia themselves and see exactly what Antonio will do to help Bassanio succeed.
Scene three, the last scene of act one ends with a rhyming forwarding couplet
Antonio: Come on, in this there can be no dismay,/My ships come home a month before the day.
Scene one of act two introduces the prince of Morocco, a suitor for Portia. He and Portia discuss the famed test that all the others have failed but we do not get to see it until later in the act.
In scene two, Grantiano insists on accompanying Bassanio to meet Portia. It is pointed out that Grantiano is not the most civil man. Grantiano promises to be on his best behavior. A forward is set up to see if Grantiano will keep his promise or create trouble for Bassanio with his behavior.
In the last scene of act 2, Bassanio’s arrival is announced. We have to go to the next act to see if he passes the test we’ve already seen two suitors fail.
Act 3 begins with the news Antonio has been unsuccessful at sea. Shylock hears this news at around the same time he hears about his daughter Jessica running off with a Christian. A forward is created here to see how Shylock will exact his revenge now that he has the opportunity.
This is followed with Bassanio hearing about Antonio’s misfortune just as he’s won the hand of Portia. The forward here being how Bassanio plans to save his friend.
At the end of act 4 after the major conflicts have been resolved we are propelled to read the next act when Gratiano and Bassanio, are tricked by their wives, who are in disguise, into giving up the rings they have sworn never to take off.