Also just to clarify why: My New Wand says Star met Marco on the first day of school, in her diary. Now some people have said she could just mean HER first day of school, but she literally wrote the word "the." A pep rally/footgame a couple episodes later also implies she came early in the school year, and the book showing Star and Marco in the freshman class and Starcrushed featuring everyone talking about summer implies the series has taken place from about August/September to May/June.
I think it's possible for all the S1 episodes to occur before Halloween, but there's no way to make that jive with Gift of the Card supposedly being before Halloween but also explicitly stating Star's been on Earth for over six months already (as the six-month anniversary card had almost expired so Marco must have had it a while).
So Girls' Day Out/Hungry Larry would pretty much either be out of order, occurring immediately after Storm the Castle/My New Wand (and the other S2 episodes then follow in roughly the same order) or if Star ever returns to in Earth it could be in the future.
More likely, though, it's just a "holiday special" thing that makes no sense for the timeline but exists because the crew wanted to do a Halloween episode.
Everything we've seen implies Star and Marco are still in ninth grade by the last finale; Hungry Larry is literally the only thing that makes the timeline wonky at all.