Mike,

I am assuming you'd have gained significant insights on the probable demand for your application. If I build, they will come could be a fatal proposition to presume. I am telling this, both, after having worked with numerous entrepreneurs as an independent consultant to working with startups as an agency.

Secondly, as a yet-to-be-launched-startup your concern should be "How to monetize the App?" than thinking about something as big as branding. Branding is much more than mere having a logo.

Continuing with sprint up to MVP could be a good idea as long as you are clear with "Objective" and "Goal" that you wish to achieve post reaching MVP stage. If not, then you should simultaneously start establishing a business model around your idea. And, don't confuse business model to means to just earn revenue. It's much more than that, and in it's absence the road ahead may be ridden with more potholes.

If investment/funding is at the top of your mind, post MVP, then you should consider putting together a document highlighting following:

1. Problem your application will address
2. Value associated with your product
3. That there's a demand for such application (I have mentioned demand and not need)
4. Your strategic planning for future on utilization of fund
There could be various such critical business parameters to consider.

I hope above could be of some help to you. Please feel free to reach out to me for any specific input that you may be looking at. Receiving more Clarity from you will help me to provide more Clarity on way forward. We call it "Hand-Holding". Thank You!!