is my starter done?

hey all,

i made my first yeast starter last night with the plan of refrigerating it tonight, decanting and pitching it into a brew that i will be making tomorrow afternoon. thing is, i think the starter is still working. it was slow to get going, i think because my house is cold, but i started noticing more growth at the bottom when i placed it on top of my cable box (which heated it up to a kinder temperature). now, little pieces of yeast are "jumping" up from the cake at the bottom and falling back down. pretty cool to watch! does this mean that yeast is still growing and i should let it hang for awhile longer? or should i toss it in the fridge before bed tonight? i definitely want to decant the starter wort, just trying to figure out timing since i don't want to stay up all night.

thanks.

Is it ale yeast or lager yeast? If it's ale yeast and there is not a big foamy krausen on top then it is probably ready to cold crash. If it's lager yeast then I don't know what to tell you because I don't brew lagers.

I usually chill them when the starter is starting to clear. If the top few inches of starter are clearer than the rest, then chill it.