You can’t really ruin sourdough imo 
Ah yeah, I forgot about the shaping before it goes in the fridge. So after the couple of hours turn it out onto a floured surface and with floured hands shape* into the desired shape and put into a floured basket or bowl with tea towel for it to go in the fridge.
In the morning, turn it out, slash it and bake straight from the fridge
* this is a huge topic