There is no minimum. The answer doesn't lie with how large your product catalogue is but your product differentiators. You can open a store with a single decor product for that matter.
Instead of looking at volume, think about these aspects:
- quality: is my product better? And how so?
- price: is it more competitive than similar products?
- innovation: does it have innovative features other don't?
- service: is my service better to influence the buying decision?