I started this habit myself a couple epochs ago. And I've been periodically increasing the daily savings amount (in fiat; not in BTC!) as my income grows. It takes about 45 seconds a day (generate invoice in one app, pay invoice in another). It's always been around 2% of my income. Very small risk. It feels good; like I'm honoring my grandmother's advice to my younger self to have and use a piggy bank "for a rainy day."
The routine taught me a single, central lesson that keeps getting reinforced: #fiat savings isn't a real concept, #bitcoin is the only real option for redeeming the work you do throughout your life.