Solo dev, first ever launch tomorrow — what's the one thing you wish you'd known?

After months of building nights and weekends, I'm launching tomorrow: Auto Invoice Generator, a desktop app where the AI runs entirely on your device (llama.cpp), so invoices and client data never touch a cloud. Teaser: https://www.producthunt.com/products/auto-invoice-generator

I've done what the guides say. But I figure the guides never tell you everything. For those who've launched before: what caught you off guard on the day? What would you do differently the first time? Grateful for any wisdom 🙏