For the past few weeks I keep my starter (goldrush) at 16C (60.8F) and feed it once a day in the evenings around 10pm. I bake with it when it doubles or slightly more (12-14 hours). I collect the discarded parts and those will develop a layer of liquid on top in another day or two... This week I skiped one feed and the starter continued to raise. I gave a stir once in a while when I'd notice it reached too close to the upper limit of the jar. It kept growing... Overnight it overflow then started to deflate. 

My question is: How can I know if my starter is ready to be used ? Or more speciffically, how do I know when is the best way to use it ?