Soak rice in 2 cups very hot (not boiling water) for 2 hours (amount as original recipe is written // use 1/3 of the total water if altering batch size). The rice should be soft but still very raw - you should be able to snap a piece in half with your fingernail without much effort. Drain and add to a blender.
Add 4 cups water (amount as original recipe is written // use 2/3 of the total water if altering batch size), dates, vanilla, and the cinnamon stick, top with lid and cover with a towel to ensure it doesn't splash. Blend for about 1 minute until the date specks are very small and the mixture seems well combined. It doesn't have to be 100% pulverized.
Scoop out a small sample with a spoon to test sweetness. If it's not sweet enough, add more dates (or honey if not vegan).
In two batches, pour the mixture over a bowl or pitcher covered with cheesecloth, a nut milk bag, very thin towel, or a clean t-shirt or clean pair of panty hose (a tip I learned from My New Roots). I wrapped a rubberband around my bowl to ensure it didn't come loose, but this isn't necessary.
Strain the mixture until only pulp remains in the cloth, squeezing to get every last drop out. It will take a little effort depending on how pulverized your pulp is. Rinse out cloth and set aside for washing.
Next, stir in almond milk (optional), whisk and transfer to mason jars or a large beverage container with a lid. Chill and serve over ice. Will keep in the fridge for several days.
*You can sub 1/2 tsp ground cinnamon for the 1 cinnamon stick. *Nutrition is a rough estimate.