To begin with, what do you suppose most agents consider the highest priority with respect to securing work for their clients?  It's not difficult to figure out when you consider an actor would have to work nearly a whole month on an Equity stage before he or she could make the same kind of money from working a mere day or two on a TV series or film.   

In plain language, the good bucks are made around cameras.  Thus, one of the best things actors can do for themselves is make sure they have a rock-solid foundation in film acting technique.    

Unfortunately, a lot of beginning actors don't see things this way.  They think acting is acting--that it's all the same.  Having done a fair amount of plays and dabbled in a workshop or two, they rush out head-strong, into the film and television job market.  Doing this long before they thoroughly grasp the distinct refinements of film acting, they fall flat on their face in auditions by giving inconsistent readings--scenes punctuated by painful moments of disproportionate largeness.  Subsequently, if word gets back to their agent (as it usually does) that they need more training, then what possible incentive would that agent have in getting them more auditions?    

These impatient actors fail to see the big picture. It could be well over a year (or more!) before casting directors would take another chance on seeing someone who essentially wasted their time.    

Moral of this story?  The industry is too tightly knit, and the memories of casting directors too long for you to make the costly error of getting out too soon.  Casting directors compare notes, especially about newcomers.  If your name comes up during their conversations, you'll want it to be for the right reasons!   

Dare to ask your teacher or film coach if he or she thinks you're ready. If they're experienced, they'll know. Until then, study your craft as if your life depended on it. Because for the life you dream of, it does.