“[Bilbo] did not remember things very well, unless he put them down on his Engagement Tablet: like this: Gandalf Tea Wednesday. Yesterday he had been too flustered to do anything of the kind.”

The Hobbit, “An Unexpected Party”

One last note - Assuming the film's opening scenes took place on/around April 25-26 (though there's no evidence of any attempt to maintain the established timeline of events, but just for the sake of speculation), then Bilbo's plans were likely interrupted. In the film, we only saw him visit the market, fearful of bumping into Gandalf again, before the dwarves' arrival that evening and his spontaneous departure in the company of Thorin Oakenshield the next morning. Hopefully Bilbo's input was not missed at the erosion meeting in Michel Delving!

“I went off at once to have a look at Bilbo... But he was not at home. They shook their heads in Hobbiton when I asked after him. ‘Off again,’ said one hobbit. It was Holman, the gardener, I believe. ‘Off again. He’ll go right off one of these days, if he isn’t careful. Why, I asked him where he was going, and when he would be back, and I don’t know he says; and then he looks at me queerly. It depends if I meet any, Holman, he says. It’s the Elves’ New Year tomorrow!’”

In my last post, I mentioned Gandalf missing Bilbo on a prior trip through the Shire. That reminded me of a glaring omission from the April calendar: Yestarë, or the Elven new year. We know Bilbo knew of the occasion and, in his own way, observed it that year. In the Shire Calendar, it was approximated with April 6 (LOTR, Appendix D).

As Gandalf explained (in Unfinished Tales):

Quote

Thus there’s no need to invent a vague “Appointment at Bywater” on April 6 - or thereabouts - since that date already had significance to Bilbo. It’s highly unlikely he would have scheduled a conflicting appointment.

The inclusion of Yestarë would really help sell the calendar’s authenticity. Pending a rights issue, maybe even another little note scribbled on the margin recording the visitor Bilbo had received while away. As far as we know, Gandalf’s next visit weeks later would still be a surprise since he neither identified himself to Holman nor said he would try again to see Mr. Baggins.

Would Bilbo be participating or watching the smoke ring contest?

No, I don’t believe the average Shire-hobbit was aware of the Elves’ new year. All the evidence points to them knowing or caring very little about places or peoples beyond their borders. But Bilbo was an exception, as Tolkien made abundantly clear. How much he knew about Elves and the Reckoning of Rivendell can, I think, be inferred from descriptions of his Tookishness. As a hobbit-lad, he pestered Gandalf with questions about Hobbits who had “gone off” and he absorbed the wizard’s tales about the wide world, which surely involved Elves and enhanced Bilbo’s interest in them; as he grew older, he gleaned information from Dwarves and other travelers he met on his days-long wanderings (per Gandalf, Unfinished Tales). From this I infer Bilbo knew enough to accurately mark yestarë on his personal calendar and to have departed Hobbiton for the occasion.

Perhaps I should have used a modifier to specify the glaring omission is apparent to me. This is how I’ve always understood Bilbo’s knowledge of Elves before ever visiting Rivendell.

“No presents were given at or during the celebration of Hobbit weddings, except flowers (weddings were mostly in Spring or early Summer).”