It's good advice to find product-market fit before rushing into business model:

Getting product right means finding product market fit. It does not mean launching the product. It means getting to the point where the market accepts your product and wants more of it. That means different things in consumer, saas, infrastructure, hardware, etc, but in every case you must get to product market fit before thinking about anything else. And, I believe, moving to business model before finding product market fit can be the worst thing for your business.