Squeeeeeee!!!! It totally worked!

Thank you so much to everyone who has answered my questions! I started the 123 Sourdough recipe that someone recommended with yesterday afternoon's discard and my bread actually rose and everything. 

I converted my 67% hydration whole wheat starter to 100% by adding 33% of the starter's weight in water and ended up with 268g starter, 536g water and 804g bread flour. I mixed it all to make a rough dough, let it sit for about 35 minutes, added 18g salt and kneaded for a but in my KA. Then I kneaded on the counter for a bit, and then did four stretch and folds about 20-30 minutes apart (I was making dinner, clean up, bedtime stuff all at the same time). They I put it in a bowl to proof at room temp for a few hours. I wanted to know if it was going to rise, as my first attempt didn't. Then I put it in the fridge overnight. It definitely doubled in volume. I shaped it into 3 free-standing boules (I totally propped up the sides with plastic children's cups turned upside down ;) ) this morning and put them back into the fridge as we had swim lessons to get to. Pulled them back out and let the proof until they seemed ready, put them into a 500-degree oven in a baking stone and with a steam pan, reduced temp to 450 and baked on parchment for 12 minutes, removed parchment and rotated loaf and baked for another 20 minutes. 

I'm sure there are nuances of flavor and texture to finesse as my starter matures, and my scoring is still fairly abysmal, but all in all, I am pretty darn pleased. 

Thanks again so much!