Mike,
I was told not to drink anything for 4 hours before treatment, but I never followed that advice.
I didn't have a problem holding for 2 hours, but now I'm wondering if I should have let it go sooner, as I have developed what appears to be a toxic reaction to the BCG's (it's rare, so don't freak).
I burned really, really bad while holding it in, but it was a steady burn, like holding hot coals. I bled pretty bad, too.
You might think about drinking water after the first hour to get a good start on flushing the BCG out of the bladder. It's just a thought, and was recommended to me by the clinic nurse.
Not sure that it would help the burning, but, I don't see how it could hurt.
Good luck and keep us posted.
Rosemary