Office hours sourdough boule

This will be my first sourdough try. I'm not completely sure about how to use the starter now that it's healthy and happy. Also, I have very little time in the mornings and about 4h between work and going to sleep, so to avoid waiting for the weekend, and based on this http://weightloss-slim.fit/node/42543/wallnut-sourdough-bread%3C/a%3E...%3C/p%3E%3Cp%3EThis is my Plan:

- 200g Sourdough Starter

- 350g warm water

- 600g flour (400 bread flour, 200g whole grain wheat)

- 2 tbsp Sunflower oil

- 15g Salt 

- 115g sunflower seeds (maybe)

1 - Feed the sourdough as usual but instead of discarding (making pancakes) Feed the 100g "discard" with 50g flour 50g water.

2 - Wait 4h for the starter spawn to grow. (Is this called the "sponge"?)

3 - Mix all ingredients, knead. Form the dough into a boule and put into a bowl and lid on, let it sit at room temperature for 2 hours and put it in the fridge for 10 hours.

4 - In the morning shape into a boule, put in floured banneton, wrap loosely in a cotton kitchen towel and put in a plastic bag and into the fridge to proof for 12 hours.

5 - Bake.