Yeah, it's 1-3 days before it and now that's how I'll remember when summer starts

We can't have summer until we remember the injustice of slavery and the freeing of a quarter million slaves in one of the last bastions of that deplorable practice

Oh, you're playing with fire trying to be pedantic like this. You're using the astronomical definition which starts on the solstice (some astronomical definitions treat the solstice as the center of the season, but starting at the solstice is the predominant one). Multiple countries use the meteorological definition which includes every day within three months (June, July, August in the Northern Hemisphere). The US has no overarching legal definition, but for example, US maritime law gives a batshit definition of summer as "April 1 to October 31" and winter as all the rest. And culturally in the US, summer tends to start at Memorial Day (e.g. this is when outdoor public pools usually start opening).

There's no "technically" here, or if there is, you're just as right as you are wrong. If anything, given a cultural holiday, it's arguably most "correct" to assess it using the cultural definition.

Kids are out of school. It's summer.