How long in fridge for starter to have yeast drop?

Normally I just pitch my whole starter as I feel 2-3 liters in 10 gallons won't affect too much. However I am doing a 5 gallon batch of doppelbock and feel 3 liters into 5 may be more noticeable.

So two days ago I pitched WLP833 into 2 liters of wort and put it on the stir plate. Last night I added 1 more liter of wort. I will be brewing tomorrow morning. If I put the starter in the fridge tonight will the yeast fall to the bottom by the morning or should I put it in the fridge now?

It will probably drop out within a few hours, when the starter temp equilibrates with your fridge. However, putting it in the fridge now will give you more assurance.

Depends on the yeast. 833 is my lager yeast, give it at least 24 hours in the coldest part of the fridge.

Unless you can chill to 40some odd degrees out of the kettle, you should be pitching relatively late tomorrow, no?

I plan for 48 hours. I've found 24 isn't always enough time.

I give mine 24 hours +/- in the fridge before decanting the liquid.

Overnight would usually be adequate, it depends on the yeast and how pedantic you want to get about all of it settling. If you can give it 24hours, if not as long as possible.