I the past I rushed with implementing ideas because I have available skills but those were all projects which either nobody needed or wanted to pay for. That moment I decided I'll not proceed unless I have a solid understanding of the audience and potential customers.

I have an idea for a SaaS product for recruitment departments which I want to kick-off as a side project first. I was able to reach out to a couple of recruiters to validate the idea and got only positive feedback. However, those all were employees, which although are my users, aren't my clients (employers mostly) who would pay.

Where does idea validation ends? Is it just some feedback or LoI from a potential customer is a must? How do I know my idea is worth trying?

I did a landing page with a contact form and my idea was to buy some ads on LinkedIn & contact companies directly with a link. However, I am pushing back on it because I feel like gathering contacts in such a way is useless because it would take month to deliver MVP and by that time most of those will likely evaporate.