How do I know my kombucha is fermenting properly?

Look for the beginning of a new scoby forming on the top of the kombucha, this is the baby scoby and will look like a jellyfish. If you see the development of brown stringy things under the scoby this is the yeast developing. Additionally, once you hit 8 days and begin to taste your brew you will start to notice the vinegar notes which are from the fermentation process.