Turn the oven on for a minute or so, then turn it off again. This will warm the oven and make it a great environment to raise bread. If you can't comfortably press your hand against the inside of the oven door, the oven is too hot. Let it stand open to cool a bit. I'm continually amazed at the elegance of sourdough baking .
Bread is simple and yet it's one of the most satisfying foods there is, and the most fundamental.
I look forward to hearing from you.