Edison
Regular.
Just a thought, you might get more responses by posting this as a new topic, or somewhere more specific (this thread is a long running one pretty much solely to do with what you've been up to in the brew house today).D
Did you get an answer ? I have the same question. I've made a 1.5L starter for the 1st time, gave it 24 hours on the stir plate, simply because white labs suggest 12-18 hours for a 1L starter.....
My 50p worth, if im making a starter, its usually 1.5L in a 2L erlenmeyer on the (homemade) stir plate. I boil the wort (from DME) with a drop of Antifoam to prevent it boiling over. Once cooled I'll add the liquid yeast and run it for 18-24hrs. After a few hours I can see tiny bubbles swirling around (quite subtle). In the morning the bubbles are no more and sometimes (depending on the strain of yeast) they're replaced by tiny clumps of yeast. They seem to have replicated as much as they're going to and are trying to floculate out.
I'm yet to see any krausen in the flask, let alone overflows, this may be due to the Antifoam though.
From there I'll pop it in the fridge to settle and bring it back out, decant the old wort and get it ready to pitch into the next beer-to-be.
In my experience, 18 hours is enough.