I should have posted a month or 2 ago. But maybe there some of us who still have fruit to thin.
Japanese Plum, Ume (actualy an apricot relation) never ripen to anything one would want to eat out of hand. They are all picked green and preserved. One easy way to preserve them is to make Umeshu or Plum wine. The recipe is as simple as can be. 50% fruit 50% rock candy and cover with grain sprit like vodka.
Here is my Goumi version with about 4x more vodka then necessary.
How long it takes until done?
I never really thought about it. I looked it up and most 5 months seems to be the minimum. I start serving it around thanksgiving so that seems about right to me. I personally have never had enough plums so I make mine with strawberries blueberries and blackberries.
Here is a recipe I found online: https://www.japanesecooking101.com/umeshu-plum-wine-recipe. They say 6 months minimum but better wait for one year or longer.
I have tons of green plums from thinning, will try this recipe next year.
It’s basically the same method I do to cure olives, only using sugar and vodka instead of salt and water. 
do you serve chilled, and is it intended for taking shots?
You pretty much have really flavorful syrup when your done.
1/3 Umeshu 2/3 sparkling water or lemonade is really good.
You can serve it over shaved ice
