This depends on a lot of factors. Many people can cleanse before going out, enjoy the evening and still be primed for playtime. You’ll want to make sure your bowels are regular and watch what you eat–sometimes processed foods, artificial sweeteners, fermented dairy products, spicy foods, and oily/greasy foods can change your routine for the worse.
The rectum is normally clean up until you feel the urge to “go,” so you should be fine for some time. With that said, try it on your own one night and use the butt plug / toy test (lubricate, insert, remove, and then examine it for the presence of debris). You should be able to see if you’re prepared to bottom.