The people I know who have started formats have started by teaching locally very successfully, and then have created day-long CEC events to teach others to teach their format. That means, you’ll have to get your format vetted by ACE and AFAA or other CEC providers.
Next step = fitness trade shows and conventions, to get instructors outside of your area to know what you’re teaching.
Another thing some places seem to be doing are in-house certifications. In order to work at studio X, you have to have the certification created by studio X. LA Fitness does this. Orange Theory does this. So another alternative you have is franchise your studio concept, including the training for how the instructors should be trained as part of the bundle.