First of all, don't ever expect to have a BM immediately following a colonic. If it was a good colonic, all your prior meals have been cleansed out and there's no reason to have another BM for at least 24 hours. Measure the time between your first post-colonic meal and next BM, that is your average transit time. If it's greater than 24 hours, then you do need to do regular bowel cleansing and general management to ensure that all of the previous day's meals are OUT of you by the end of the following day.
To do that, please refer to the Bowel Management notes in the FAQ for this page. There you'll find plenty of safe recommendations. Stay away from psyllium until things start moving, if you take psyllium without taking in enough water it turns into cement. You should only ever take a flat teaspoon of psyllium, preferably mixed iwth other fibers like flax seeds, vegetables, dates, prunes, etc.