I built a free tool. How should I monetize?

Hey, everyone. I can really use your feedback.

So, I created https://fillvisa.com/ - its a free website that helps immigrants (and lawyers) easily fill USCIS forms. Traditional PDFs are very difficult to fill. Our web forms provide better UX, and the user gets the filled PDF as output.

I shared it with immigrants, they loved it.

Now, I'm building a paid version (https://plus.fillvisa.com/) of Fillvisa. This is intended for Immigration lawyers.

Thing is, SaaS is gonna take sometime to get published and become profitable. I'm looking for immediate cashflow.

I was wondering: if Fillvisa (free version) starts gaining traction, can I leverage it to get paid software/web dev gigs from law firms/businesses?

Does anyone have any experience of:

• created free tool/product
• gets traffic
• leveraged that for paid services