It starts within 10 minutes of being plugged in. Just saying “randomised starting time” is misleading, it starts randomly within 600 seconds.
Can’t touch you if you haven’t got a Smart Meter. You were warned!
Can’t touch us either, despite having a smart meter and charging point. See, what you did there with your “warning”, is potentially prevent people from getting a charger before this law comes into effect. Which makes them, much like we are, exempt from it.
Since it doesn’t appear to be clear, those new regulations only apply to chargers installed after the 30th of June. Or, to put differently, not a single private charger currently installed in the UK is affected by this.

Prior: SEAT Ateca Xcellence Lux 1.5 TSI DSG MY19, VW Golf GTE PHEV DSG MY23
Current: Hyundai Ioniq 6 Ultimate
Next: we'll see what's available in 2028.