Stepped Starter

I've started my first step on a stepped starter for a vienna lager using white labs german lager yeast. I've added 100 grams of dme to one liter of water and have it at 12 celcius. I have an aquarium air pump aerating it constantly. It's in a one gallon glass container and I plan on 3 stages of one liter each. I only want to cold crash and decant at the end. I need a rough estimate when I should add each stage.

I usually do 24 hours per stage.

Ok, thank you.