Stage 1 - You have an idea, and that's about it.
Stage 2 - You have an idea, a plan, and are ready to get started, or maybe have even taken a few steps on your own.
Stage 3 - You've built the foundation for your business, and are ready to accept customers. You might have some sales already, or you might be waiting for that first customer.
Stage 4 - You've built out your business, learned from some trial and error, and have had some customers already. Now you're ready to take things to the next level.