It's more like 24-28 hours from 0-100%. 28.9 kWh (usable battery) / 1.2 kW (10 amps @ 120 volts) = 24 hours, but also assume ~ 85% efficiency and/or less than 120V to the house.
Though like you said, most people don't roll in at 0%. Some of my trips take as little as 4% (a 6.4 mile round trip from today, with a good bit of unnecessary acceleration).
The
Tesla system with swappable NEMA adapters would be really helpful here, especially since the MINI is so efficient. That would allow people to double their charge speed in most US homes after a trivial cost (5-20 receptacle swap). There is a
16A L1 charge connector on Amazon, but it doesn't have safety certifications.