The problem is that many agents will not want to train you only to have you "grow up" and become their competition.
Before I became an agent I worked as a secretary in an office. I was up front with them about my intention to eventually get a license and we had agreed that at that time I would step down as secretary and work for them (well that didn't work out so well but that's another long story). LOL
That's the tough part of this business. It's hard to be an "apprentice" because it kind of sucks to train someone and have them (directly or indirectly) use what you taught them to get business away from you...lol.
While a secretary with a license can be handy when it comes to answering mundane questions that unlicensed people are legally not allowed to answer, the other agents may begin to think you as the secretary are pilfering leads that would rightly belong to them since you're the one answering the phones and greeting walk ins. Had that happen from personal experience. Was a very ugly scene with one particular paranoid agent. She was a maroon, to quote Bugs Bunny, anyway...but still, the tension was there.
Your best bet, IMHO, would be to do some research ahead of time and decide what real estate office you want to work for. Ask other agents why they work at their office. Then talk to the managers/managing brokers and interview them - see which office will offer you the most one-on one or close to one on one training. Then when you pick your broker, tell them you want to become licensed and work for them. They may allow you to start some training before you get your license but they will probably expect you to be either in a licensing class or have already taken the class before investing a lot of time training you.
Not all brokerages offer great training, even within a franchise. Most offices are independently owned and operated and each one is run according to the way the managing broker sees fit. Some managing brokers will take a very proactive stance with their new agents and actually make sure they are trained well...others may plop you down in front of boring videos....and others may say "Just bring us the goods kid, you'll learn as you go."
There could be two Century 21 offices in your area and one will be great and one will be for experienced agents who know what they're doing because the broker is never around.... RE/MAX was supposedly meant for experienced agents only but now I do believe they take and train newbs too - but that's going to vary from office to office. Keller Williams supposedly has great training but maybe not at all offices. Treat each individual office as just that - an individual office.
Hope that makes sense.