How Soon After Taking Uristat Will The Bladder Pressure Be

How soon after taking Uristat will the bladder pressure be decreased. I took my 1st dose at 10:36 AM shortly after eating. It is now approximately 3 hrs later and I still feel a lot of bladder pressure. I am 66 yrs old. If I Recall correctly, when I used to take this when I was younger, it seemed to work faster. I will be picking up Macrobid in a little while.