Sourdough starter

I'm trying to make a sourdough starter again.  The last one I tried, a few years back, never got off the ground.  There's a recipe for a yeast-based banana bread that I want to try, and it calls for some sourdough starter.  So, I have to make the starter.

So far, it's doing well.  I've done the third day's work on it and it has shown some life.  In fact, it's shown too much life.  Yesterday, I did the second day's mixing and by the time I returned from aikido, it was already rising more than the directions said it would after 24 hours.  I made the decision to wait the full 24 hours instead of going by the amount of rise.  When we got home from seeing a play late last night, it was overflowing its beaker.  I took a little out of the beaker and returned it to its spot.

After today's mixing, it's not as aggressive as it was yesterday, so I hope it's still alive.  We'll see after work tomorrow.