If you have to hire the senior engineers anyway, why not hire only the senior engineers, at least in the early stages of the company? They'll be able to get actual work done, you'll have a decent codebase, and you might actually be able to ship a product that can get you additional funding and revenue. Then, once you've taken care of the money problem and the startup is no longer fighting for its life, you can hire some junior devs to flesh out the product and exploit market opportunities that you didn't have the resources to explore in the startup phase.