Hi Ben,
A good clean out before a session for me can take anywhere from one to two hours. I'm really anal about being clean... 😁
I normally use a shower hose in repeated rinses to shoot water into my rectum to clean as deep as possible. The last rinses which in my opinion are the most important and take the longest are sometimes achieved by pushing the lubed shower hose (sometimes with an enema head attached) as far past the sigmoid and deep up into the descending colon as possible. This helps clear out the most recent meals, open me up, help find direction and straighten the sigmoid for deep play. I try and open myself up by pushing my fingers in as deep as possible to helps release fluids from higher up...fingers get very messy but you can really get almost everything out. It starts as dark brown fluid with pieces of food from meals as recent as 5 hours before and ending up with yellow liquid until it eventually runs clear.
Unfortunately for me, we have not yet reached the elbow, but we never have a mess, only sometimes a small bit of fecal matter. We use an incontinence sheet to play on, and often use 2 or 3 in a session, so even if there are traces or blood or fecal matter leaking out with the lube, play can continue without loss of aesthetics.
I find that even with a very lean diet of fruits and vegetables, I need to repeat a full clean out if I want to play the next day. I am a bit of a slut and during the recent summer while on holiday my wife fisted me every day for 2 weeks. We had a wonderful time but I sat in the bathroom for many hours, I did however read some good books!!!
If I want to play away from home, I can stay clean for about 4 - 6 hours before I feel uncomfortable about starting a session. So if traveling, I clean out in the morning and try have a start as early as possible in the day.
Try not to go too fast and hurt yourself however as it can be quite a bummer if you're all cleaned out and ready to go but have irritated your sphincters so much that you can't play anymore...