Someone's building a commercial product for you for free? Before reserving any equity for a potential CTO (who really sounds more like the developer who's supposed to finish your product) you should consider compensating them for their work first.

If you and your future CTO will be equal partners with equal responsibilities the remaining equity should be split in half.

"Non-technical founder" often translates to "the idea guy". This might or might not be the case here but you should definitely ask yourself what you'll be bringing to the table before bringing a partner into the game. If he or she will do most of the work while your contribution mostly is the original product idea that's a recipe for trouble once business doesn't run as smoothly as you wish (which it inevitably will at some point).