Which to pursue first: idea validation vs. product MVP and going with prior research (small data pool)?

Hi all,

Been working on an idea for a while now - was working on my business plan last night and I wanted to get your opinions on whether I should validate the idea further or jump into building an MVP.

Context:

• The idea has been validated by me interviewing a handful (20-ish) prospective customers, with a resounding "yes" that I should build my application.

• The road to an MVP isn't necessarily easy but I've got a good foundation to start building something for my beta-users. I'd estimate this work at maybe 1 month?

• There's a few assumptions and missing pockets of data in my business plan, mainly around assumptions surrounding my user base and how I will funnel users to my application.

• I have approximately 250 beta-users that initially signed onto a very rough proof of concept I built nearly 2 years ago. No idea if they're still valid users or not.

So again, the question: Should I spend more energy on validating the idea and business model or start working on an MVP?

Validating the idea means:

• Building & deploy 2 or 3 landing pages
• Assembling a short survey and collecting results from the landing pages
• Re-evaluation of my business plan and assumptions