I would wait up to 3 days if I could, but it starts burning or hurting, or both, so I have to change it.
With an end ileostomy, life was good. It was perfectly flat, 1 inch tall above the skin, the hole was facing the front. This loop ileostomy I have now has a very odd shape. Plus the fluid output. Some days I need to change more than twice!
if it burns, or itches, I believe you have to change it immediately. At least, with my skin.