Well, her two year parliament expires this summer.
And she's not going to get a Queen's speech through.
And that means before the end of June.
And the only way to create a new session is to hold a general election and hope to win a majority to pass her withdrawal agreement by October.
May 2nd - Local elections likely to be a disaster
May 23rd - European elections. A nightmare
September - New parliament with Queen's speech
October 31st - Brexit extension expires
She won't get Brexit through before summer, Europe won't talk to her again before October, and she has to get a new Queen's speech through parliament in September.