Assisting?

I've been told that even after I complete school that I would need to assist for months afterwards? If this is true, how long? Also, someone else said that I could start assisting before my 1800hrs were completed? Somewhere around 1300hrs? I'm confused? How does this work? I'm guessing in order for me to learn indepth color, styles, etc, I would need to shadow or assist to learn this, just can't get a clear answer to how this whole thing works. Anyone having information on this topic I would greatly appreicate your input. Thank you!