I have a recipe for an herbed focaccia that I have been making for several years that calls for dry yeast.  I have purchased several starters which are all doing well and I would like to convert the original recipe from dry yeast to one of my starters.  Does any one have a method for doing this?

Here is the recipe that I would like to convert:

2 1/2 tsp active dry yeast

1/2 cup warm water

1 1/2 cups milk

6 Tbsp olive oil

5 cups all purpose flour

2 tsp salt

fresh herbs and coarse salt