I put on a latex glove.
Use a finger full of lube and work it in and out of the butt.
Use a second finger full of lube and go deeper this time.
Insert the nozzle and them reinsert the finger.
Open the valve and let the water flow with the finger still in place.
After the filling, remove the nozzle but keep the finger in place.
Work the finger in and out to set up waves in the rectum until my partner cannot take it any more.
Try two fingers for the second enema.