Taking a pay cut to work 4 days/week - nervous but hopeful

Just finalized the deal with my company today. I'm dropping to 80% and taking every Friday off starting next month. Yeah, it's gonna hurt our savings for a bit, but my 8yo only has a few more years before he stops wanting to hang with his old man. Financial advisor says we can swing it if we're careful. Took 6 months of negotiating but my boss finally said yes. Honestly? I'm terrified. But also kind of pumped. Has anyone else done this? What should I expect in terms of how it affects your career track?