Instant or real time reactions can occur and they are not atypical IBS symptoms. Delayed reactions can occur and they are not atypical IBS symptoms.
For some people with IBS merely the process of eating which stimulates the release of hormones and neurotransmitters that affect the colon. You may find this video interview with Prof Whorwell on Diet, eating and IBS who discusses this fact of some interest. In other instances there can be a 6-36 hour delay before there are symptoms so for people like you and I the reaction is delayed by many hours.
Yes - I have heard of Bentonite clay - an absorbent, expanding clay similar to kitty litter - commonly found in colon cleansing products which are not recommeded for IBSers. You may want to use it with caution.
It would be helpful to know what you eat for typical meals and snacks?
If you think you might have a leaky gut why not ask you doctor for a test? There are variety of ways to test the permeability of the intestine.
-------------------- STABLE: ♂, IBS-D 50+ years - Science of IBS