In Sweden we celebrate on the eve of a coming holiday. Meaning we celebrate Midsummers eve, Christmas eve the 24th of December and Easter eve.
The explanation for this might go back to the time before mechanical clocks, when sunset signalled a new day, not midnight. Which makes sense in a setting with less changes in length of daylight than the far north.
So today been full of Midsummer Eve celebrations and smörgåsbord laden with food.
Why wait for sunrise
Begin the celebration
On the eve of things