Many industries require that you go into them full-time. Not pro speaking! You can start your pro speaking career by working part-time at your business... until you simply can't afford to keep working at your old job because you're making so much money in your new career as a pro speaker!
Of course, the more time you can dedicate to your career, the sooner you'll achieve success. But if you can spare only a few minutes a day, then that's OK... because every single minute you spend on becoming a pro speaker brings you one step closer to fulfilling your dream!