The night before baking, make the start by combining all the starter ingredients in a medium bowl and stirring together with a spoon. Cover with plastic wrap and let sit at room temperature overnight for at least 10 hours and up to 16 hours.
The next morning, combine the start in a large bowl of a stand mixer with the rest of the ingredients. Mix with a dough hook on low until all the ingredients form a dough. Turn up speed one notch and mix for another 4 minutes. The dough should be smooth and stick slightly too the bottom. If it's too sticky, add 2 tablespoons of flour and mix together.
Grease a large bowl with olive oil. Pour out dough into grease bowl and coat completely. Cover with a damp towel and place in microwave or other draft-free spot to rise for 45 minutes. After 45 minutes, fold the edges of the dough together by pressing into the center gently and then flipping over. Cover and continue to rise for another 45 minutes.
Flour a clean counter surface and turnout dough onto surface. Form into a rectangle and slice into three equal portions. Form each portion into a ball by tucking under the edges. Place onto floured surface and cover tightly with plastic wrap. Let them rest for 15 minutes.
Place cast iron skillet at bottom of oven and rack in the center of the oven. Preheat oven to 450 degrees. Make sure to let it preheat for at least 30 minutes before placing bread in the oven, especially if using a stone. Place a sheet of parchment onto baking sheet and set next to prepping area. Set 1½ cups to boil on the stove and keep covered until ready to use in the baking step.
Once the balls have rested, grab one and form into a cylinder. Then, flatten into a rectangle, with the long sides in the horizontal position. Pinch the two short sides together in the center of the rectangle. Fold over the top long side into the center and then fold the bottom long side into the center, similar to folding a letter. Flip over to have the seams facing down. Slowing begin to roll into an even log. Then, stretch the log until it is 15 inches long. Place onto prepped baking sheet. Repeat with other two balls. Dust all the logs with flour. Cover with plastic wrap and let them rise about 45 minutes. They won't be double in size but definitely more inflated.
Cut 4 to 5 diagonal slits on the top the loaves and then place in the oven. Pour water into the hot skillet and then close the oven door. Bake until deep golden brown on top, about 25 minutes or when centers are 205 degrees. Remove from oven and let cool slightly before serving.