I wash n go every day and even in the Winter. But if I need to get 2nd day hair for some reason what I do is use a gel to "set" my curls.
I wash hair, use a leave-in conditioner, apply natural oil (this is optional), apply gel. I either diffuse or air dry. Then when it's all dry I put my hair up into a pineapple ponytail (where you bring the hair all the way up to the front of your head in a ponytail so it looks like a pineapple). I sleep that way. The next day I take down my hair, shake it out, use my fingers to place the hair where I like, and that's it.
Some people may have to do more fluffing to get the hair the way they like it.
Products I use for 2nd day hair:
Tresemme Natural Conditioner (can use Giovanni Direct Leave-In Conditoner for this method as well)
Natural oil of my choice (olive, castor, coconut, etc)
Ecostyler Gel (the pink one with the hold of 7) or Fruit of the Earth Aloe Vera 100% Gel.
It can also be done without using any oil. If I do it without the oil I do need to scrunch out the crunch when the hair is dry. It's not a problem though..my curls still end up soft and have movement once I SOTC. I like the oil added though because my hair is dyed a matte black and the oil adds shine for me and keeps my hair moisturized longer.