I am trying to figure out the average time from starting to tremble to peeing her panties. Your best guesses please, my is 10-12 minutes.
In real-world situations, it mostly depends on the girl's will to keep holding - with a minimum of a minute or two and a maximum of until her bladder ruptures (probably hours). Some girls have better holding power than others, usually the ones I'm interested are the ones who are more likely to lose control against their own free will.
Beats me what the norm is. For me, trembling is usually the final sign. It's not much more than 10 minutes after the trembling begins, when I'll lose it.