Well, it was my first symptom even before the hot flashes or other symptoms really kicked in. I thought I had a UTI and went to the urologist. The urethra burned and when I urinated my vulva burned like a yeast infection.
It only happened when I missed periods for 2 mo or more. When the periods came back, it went away. Then when they left for good, I had it continuously. I have been checked for infections, had my bladder looked at(inside), etc and they never find anything except minimal blood cells in urine. I was treated with all kinds of antibiotics over many months and nothing helped. I started local estrogens, and eventually vagifem helped a little but the burning never really has gone completely away for good. Started HRT 7 months ago after 3 years of putting up with this burning. Still burning some but better than originally.
To answer your question....I think it comes on slowly, first dryness, some irritation, etc that gets worse.
It is hard to separate the urethral and vaginal symptoms, they sort of overlap. You will know something is up down there though. If it stays untreated for a while, it gets worse and can take weeks/months to reverse.
Andius