I did this by feel mostly. Here are the proportions I used:
1 1/2 cup sourdough starter
4 cups bread flour
1 tsp salt
1/2 cup sugar
2 tblsp walnut oil
1/4 cup canola oil
1 cup Warm water
You can see the starter on top.
I left it out to rise overnight.
Shaped challas and bilkeluch then gave it a good 3 1/2 hour rise.
לכבוד שׁבת קודש!