Originally Posted by anbowden
Isn't it helpful to measure the final gravity to know when the starter is finished? Or am I over thinking this?
It'll be done in 48 hours, probably less. Even if you cut it off a smidge early, your goal here is to grow yeast, not ferment beer. The bulk of the yeast growth happens before active fermentation even starts.
Starters get pretty rote. I do 100g of DME per 1000mL of water, use volumes as dicated by yeastcalc.com, and let the thing go 2 days on the stirplate and then 2 days in the fridge. Decant off the spent liquid and pitch on brewday.