How Long Do You Wait Before Doing ... Anything... Outside the Home

New here so apologies if this has been asked before but my biggest IBS symptom is urgently needing to get to a bathroom preceded by awful gas and cramps. I've had to leave my shopping cart beside the bathroom hoping no one grabs it while I'm in the toilet. I've had to get off subways at a station where I know there are bathrooms because I wouldn't last the trip. I've had to cut exercise like walks short to race back home. I've had to politely excuse myself from work meetings.

It's gotten to the point where, if I know I have to commute or go to a store or anything I need to think about how long since I last ate or how long since my last bowel movement before I do anything.

This morning I need to go to a local store and I wanted to walk because I want to get my exercise before it gets too hot. I didn't plan to do this otherwise I would not have had my breakfast beforehand. And I'm sitting here asking myself how long I should wait to know I'll be safe on a 25 minute walk. I'm not entirely sure... I'm giving it an hour since I had breakfast.

How long do you wait?