I, personally, like to enroll around 200 students each month. The competition on Skillshare can be tough depending on what niche you try to get your class to trend in. I would even suggest you see how saturated the niche is for your specific class topic on Skillshare before you start recording.
Don't give up though, always aim to improve your classes.
As of October 2016 there are over 2 million students and 10,000+ classes.