The Halacha, according to the Mishna Berurah, is that you have until the next time you have to use the bathroom, no matter how many hours later it is.This is what all of you were saying (DY, Meno and Lubavitch Rabbi), but I’m not sure if it was clear.
Hope it’s clear now. Is it, LB?
That is why it’s best to say the bracha right away (in case you have to go to the bathroom again and then you won’t be able to say it anymore).