Voice over talent are actresses and acquiring positions is dependent upon how competent you are at drama. You should maintain intensity, believability & improvisational abilities of a professional stage or screen performer. Really the only distinction is that you will work behind a microphone, not a camera.
Put together, your initial training might take months or years. Full concentration is required for becoming successful. Meaning rehearsing your abilities as frequently as you can. One of the biggest misguided beliefs about this business is the time it will take to be a functioning talent. You will find few specialized work opportunities that don’t require a qualification or a conventional college level instruction.
Even so, whilst you might not commit 4 years and tens-of-thousands of dollars into a steady voiceover education you have got to invest a few years of part time study and a few thousand dollars to be well prepared. If you want to race through your studies it likely means you’re unwilling to learn all that is necessary for success.