The starter is definitely in the fermenting stage, but is not yet "rising and falling in a predictable manner." In fact, it's not really rising and falling at all. That seems to be because the "balance of yeast and bacteria" is not yet firmly established.
Did you know that the mascot of the San Francisco 49'ers is "Sourdough Sam"? I didn't.
Did you know that "sauerteig" means "sourdough" in German? I don't think I knew that, but it's not really a surprise.