It can be inferred that Theseus is waiting with anticipation for his marriage to Hippolyta as the play opens. Anticipation means to expect and/or to hope for something. Theseus does not say it explicitly, but he certainly explains that he is looking forward to the day of the wedding, which is only four days away. Evidence from the text that helps the reader or audience to know that Theseus is excited for the wedding to happen is in the first lines of the play.
"Now, fair Hippolyta, our nuptial hour
Draws on apace. Four happy days bring in
Another moon; but, O, methinks, how slow
This old moon wanes! She lingers my desires,
Like a stepdame or a dowager
Long withering out a young man's revenue" (I.i.1-6).
In order to understand how Theseus explains his feelings, one must look at the imagery presented that represents time or waiting for time to pass. In the first line, "nuptial hour" means wedding plus time. The next phrase that follows describes how the nuptial hour is moving--by drawing on for a longer period than desired. Then Theseus says that the old moon is slow. This means that the current month, as symbolized along side the moon's rotation, is passing too slowly. A new moon also means that a new month approaches. But Theseus says that the old moon lingers, or is not moving quickly enough for him.
Finally, he compares his feelings to an old woman who must be useless because she seems to be wasting her dead husband's money on her own life's existence. Theseus, therefore, is ready to move on with life. He's ready to start his new life as a married man to Hippolyta and can't wait for the old to die so the new can begin.