If you can get the customers to pay before get a CTO, you can give him 10-20% and a good salary. If not, at least 50% and you will have a hard time convincing someone good enough to help you achieve success.
This is not what I suggested . If you want a junior as CTO you can find some in dev bootcamps, universities or startup events.
Could a developer do your job plus his own and thus own 100% of the business? Some developers can sell too.