Can't Wait For Starter Semi-Sourdough Bread

Herbert, my sourdough starter is still a very young starter (today is his 4rth day of life). But I found that I can't wait any longer - at this morning's feeding around 8:30 am, I put 1/2 cup of starter into pancakes, and 1/2 cup into a new bowl. I fed both bowls.
About 3:30 pm today  I started making a semi-sourdough bread out of the very short-lived Hebertson while Herbert continues to mature. (Herbertson seem to have a bigger chunk of starter, he was more lively than Herbert.) Herbertson baked up like this:

Ingredients:

• 10 ounces lukewarm water
• 2 teaspoons instant yeast
• 12 ounces “4 to 6 hrs since fed" sourdough starter
• 2 tablespoons sugar
• 19 1/4 ounces all purpose flour
• 2 teaspoons salt   
    
• Optional: 2 teaspooons melted butter

Instructions:

1. Sprinkle yeast and sugar on lukewarm water in stand mixer bowl, blend in sourdough starter and 1 cup of flour with whisk or spoon.
2. After well combined, add in rest of flour, kneading for a minute or so.
3. Sprinkle in salt, and continue kneading on medium-low (3 to 4) for 4 minutes, forming a smooth and somewhat sticky dough.
4. Spray one hand with cooking spray, scoop out dough as best possible.
5. Use cooking spray to lightly spray bottom and sides of bowl.
6. Allow dough to fall back into bowl.
7. Mark current volume, and volume to double
   (Mine was a bit under 4 cups, maybe 850 ml)
   
   
   
     
8. Cover bowl, let dough rise until doubled
   (This should be maybe 90 minutes, depending on how active your starter is.)
9. Place parchment paper at bottom of a enabled Dutch oven, sprinkle with 1 teaspoon semolina flour.
   (This is to prevent burning when cooking.)
10. Gently shape dough into a ball, place dough ball in Dutch oven on top of semolina flour. 
11. Cover Dutch oven with lid, allow dough to rise for another hour.
12. About 45 minutes into rising, arrange racks of your stove to support Dutch oven centered of oven. Preheat oven 425.
    (Move racks as needed)
13. Remove lid, make 2 slashes on top of bread just before baking with a very sharp knife.
    (Optional: Spray lightly with cooking spray, sprinkle with a 1/2 teaspoon of Kosher salt)
14. Replace lid, place Dutch oven in stove.
15. Bake for 25 minutes, remove lid.
    (Optional: Brush bread with 2 teaspoons melted butter to promote browning.)
16. Bake for another 5 to 10 minutes until it is a deep golden brown.
17. Remove bread from the oven, and cool on a rack.

Carole's Notes:

Recipe is lightly adapted from http://www.kingarthurflour.com/recipes/rustic-sourdough-bread-recipe
I decided to use all the cloned starter in this recipe to amp up the sourdough taste. I cut the water and flour in the official recipe to take this into account. The bread was tasty  - it made a lot!