Converting 12H biga + yeast Swiss Bürli recipe into overnight retard method

Hello

I have this recipe of Swiss Bürli which uses 12H room temp preferment and yeast.

I'd like to convert it to the overnight retard without preferment.

Do anyone have a formula to culiculate the yeast amount?

The Bürli is the bread often eaten with Bratwurst or Servelat like this:

I found the way to convert direct dough to overnight retart, thanks to some experts on this forum but not one with preferment.

Swiss Bürli (from Richemont Fachschule textbook "Schweizer Bäckerei")

preferment:

1000g water

10g fresh yeast (therefore, 4g instant yeast)

1500g Halbweissmehl (this is half way between AP and WW flour, extraction 75%, protein 12.5%)

20g Levit (this is powdered sourdough + some enzyme)

rest for 10-12 hours

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Dough:

all the preferment above

2000g water

80g yeast  (so, 32g instant yeast)

100g salt

2250g Halbweissmehl

1-2H ferment @71-75F, then shape, bake.

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Flour to ENTIRE yeast ratio is: 0.95%... but I guess this doesn't help since preferment is left for 12H.

Thank you so much!