In a 16-ounce covered container, stir together the oats, chia seeds, coconut, salt, and Greek yogurt (if using).
Add the milk, sweetner, vanilla (if using) and stir until the mixture is well combined and there are no clumps of chia seeds.
Cover and refrigerate for 15 minutes, then stir again to make sure there are no clumps.
Cover and refrigerate overnight, or for up to 5 days.
In the morning, top with your desired toppings.