Large loaf with high 90% hydration soughdough baking time.

Hello bakers and enthusiasts! I have been reading your discussions for couple of months now. This website is an excellent source of information and various views, especially relating to soughdough baking. This evening, I am going to bake a highly hydrated soughdough, following Yohan's advice. His formula includes 90% hydration with 2% starter and 24 hours fermentation period. As I am not very experienced person, I need to know what is the best way of baking it? My plan is to bake it in a iron cast le casserole at 250 C. Due to the fact that I want to make a large loaf in one go (my dough is 1000 gr flour and 900 ml water), my quiery is how long shall I bake it for, provided that it is a relatively big piece? Should the le cassarole be necessarily preheated? Or is it acceptable to add the dough in it for final proof and then put it in the preheated oven? Thanks for your your thoughts in advance!

You don't have to go up to 90% hydration, If you're going for all bread flour then 75% hydration works very well too. And watch the fermentation as when I have done the recipe often 24 hours can be too long.

Which flour are you planning on using?

Thanks for your response. I am attaching the pictures of my yesterday's attempt. For the recipe I used, 900gr water, 600gr organic white flour (12 protein), 400gr wholemeal flour (14 protein), 8gr starter (three months old, usually fed as follows 1.1.1, every 10-12 hours), 16gr sea salt. The dough was fermented at room temperature (beteen 19-21 C) during 20 hours. I mixed it once after first 10 hours and did not do any second proof. I added it into a cold cast iron pot and baked it at 245 C for 20 min with a cap and another 25min without cap. I did not preheat the oven as my pot was cold, so I used the cold start method. The bread is very tasty but it is too moist inside, so I prefer tosting it a bit. I would appreciate your advice and comments on this.