I'm not a lawyer, so I'm not going to give you legal advice. Generally speaking, it's very low-risk to use a boilerplate privacy policy for an MVP.
Ideally, instead of using a service like you mentioned, you should copy and edit the privacy policy of a service that is as similar to yours as possible.
Once you make your first dollar or get your first ~10,000 users, it'll definitely be time to hire a lawyer.
Some important questions though:
1. How sensitive is your data? Is it PII (personally-identifying information)? That includes full names, addresses, phone numbers, and a complicated list of other things.
2. Are you in Europe?
3. Have you formed a limited-liability entity? In the US, that would be an LLC.