I have been very successful with irrigating in the moring, just one time. But i do it every day unless I have a very early morning and there is not time, then I just wear an open ended pouch and hope for the best. I have only tried a second irrigation if my return stops before I know it should be finished. It usually takes about 30-40 minutes, but can take up to an hour. I have experimented a lot and there seem to be several things that effect the time it takes and if I have "bonus returns" during the day. Drinking a glass of water when I get up, having a cup of coffee, then starting makes it go quicker. I use an instant read thermometer, the temperature is important, too cold and it seems to stop the muscle movement. Too hot and it relaxes the muscles and again, no movement. 75 (74.8-75.3) is my sweet spot. Maybe everyone is different. I also find it takes much longer, and I get the late returns later in the day, if I eat close to bedtime. Fatty foods can cause me to have watery return almost immediatly after eating.
It's this kind of imformation sharing that prompted me to join this site. The best tips and help I have receivd have been from fellow ostimates.