Chocolate pots de creme is traditionally made with egg yolks as an ingredient, and they don’t just enhance the flavor, but also help the dessert set well and get to that rich, creamy texture that you want.  Since this recipe does not call for the use of eggs, it pretty much relies on refrigeration for the mixture to set well, and that is not something you can compromise on. Allow the mixture to chill for a minimum of 2 hours- ideally overnight, for you to enjoy it to the fullest.