how long should i let my starter go

I've searched but haven't come up with anything. Usually I run my starter for over 48 hours, but I want to brew on Friday and I prefer decanting before using the starter.

Mr. Malty's calculator estimated I need 1.2 liters on a stirplate which is what I'm doing. I pitched one smack pack. It's been about 24hours... if I toss it in the fridge after about 30 hours, will the yeast count be high enough or should I really wait longer?

 

I think you will be fine. I have pitched before in that time line with no problems.

 

What's the problem with letting it go until Thursday night or Friday morning, it'll probably be done or mostly done at that point, then plopping it in the fridge for a couple/few hours to really help the yeast settle, then decanting and letting warm up to room temp an hour or two before pitching. That's what I do anyway, usually I'm not on top of making the starter early enough, so end up rushing things in 2 days or so.

 

I've done starters for lots of ales and have always let it go for 2 days, sometimes 1 if I forget or don't get to it. I usually make smaller starters (around 1 qt) and don't decant so if you want to build the cell count up some more and crash the temp in the fridge to settle it out 3-4 days sounds better.