Hi Caleb! These are good questions and while I think the answer will look different for everyone, I can share my experience with you for our first SaaS!
1. We built a B2B saas so we incorporated right away. Incorporating your business will protect you personally from liability (basically anything that the businees doesnt own is off limits) if a business is not happy and decides to sue you.
2. We hired a lawyer to create us a privacy policy and terms of service once we started getting over 100 users.
3. If applicable, keep up with regulations within your industry and try your best to stay compliant. We had to since our company was in Web3.
Once those things were in place, we didn't have to think too much about legal stuff outside of getting a custom contract created for a specific enterprise use case.
I hope that helps!