Hire design agency from the start for your mobile app or later down the line?

I think it depends on your resources and app scope. If you have the budget and want a polished design from the start, bringing in an agency early can set a strong foundation. But if you're more strapped for cash or want to validate the core functionality first, you could start with a minimal viable design yourself and bring in pros later to refine it once you have traction. There's no one-size-fits-all answer, but those are some factors to consider based on your situation. Let me know if you want any agency recommendations!