Did it myself. I'm sure it wasn't precisely accurate, but, good enough: just go down to the breaker panel, switch off each circuit there, then turn on each circuit individually with its usual devices connected. In the case of appliances like the fridge, stove/oven, clothes dryer, run the device with a normal load. With the water heater, I just ran hot water until it kicked on.

Then observe change at meter, write it down, and do some math.

As an added benefit, I got to verify and one case relabel the circuits.