Millie Marconi on Building an AI to Test Content Before You Post It

🎟 Live Show at UNSW – May 29Catch Georgie and Andrew McCarthy (Head of APAC at Notion) live in Sydney 👉https://bit.ly/BAI-LiveEventEpisode SummaryMillie Marconi is the founder and CEO of Yesterday, and the creator of Test Feed, a breakout AI tool that lets users preview how their content will land with a synthetic audience before posting it online. In this episode, Millie shares the story behind building Test Feed after a viral LinkedIn post backfired and sparked a personal reckoning around reputational risk.We explore how synthetic audiences are making elite-level brand testing accessible to everyday founders, why building in public is both terrifying and empowering, and what non-technical founders can bring to the AI table. Millie also opens up about her nomadic lifestyle, her favorite AI tools (Claude and Gemini, anyone?), and the unexpected upside of being “canceled.”Time Stamps02:25 – What Millie’s Building: Yesterday & Test Feed04:52 – Why Synthetic Audiences Are a Game-Changer06:14 – The Demo That Went Viral: Over 800 Signups07:58 – How a Personal Misstep Sparked the Idea for Test Feed10:43 – Who Test Feed Is For: Founders, Content Creators, and Social Media Managers13:11 – Building in Public vs. Stealth Mode16:48 – Female Founders, Visibility & Vulnerability19:52 – What Non-Technical Founders Bring to the AI Era22:45 – Integrating AI into Test Feed as a Non-Technical Founder26:20 – AI Tools Millie Loves: Claude, Cursor, Gemini, and More33:43 – Just Play: How to Get Started with AI Without the Overwhelm36:06 – Digital Nomad Life: Lessons From 2.5 Years on the Move42:17 – Rapid Fire: Guess That Cringe Tweet (Trump vs Elon Edition)Resources🙋‍♀️ Follow Millie on LinkedIn - https://www.linkedin.com/in/millie-marconi/💼 Yesterday Testfeed - https://yesterday.work/🧵 Millie’s LinkedIn Post on “Masculine Energy” - https://www.linkedin.com/posts/millie-marconi_after-interviewing-100-hr-leaders-about-activity-7284745207923781632-QU-X?utm_source=share&utm_medium=member_desktop&rcm=ACoAACb9cQIBMRvkSzVlzjznYUqzAEsWp-Q5zBo✨ Connect with Georgie HealyWeekly Substack: https://georgiehealy.substack.com/Linkedin: https://www.linkedin.com/in/georginahealy/Instagram: https://www.instagram.com/georginahealytech/The Day One NetworkIn The Blink of AI is part of Day One, the podcast network dedicated to founders, operators & investors.Sign up to get your weekly insights into the up-and-coming AI startups: https://dayone.fm/newsletter Mentioned in this episode:Deel x PX_Post Intro