As others have said, I guess I see this as something that's pretty personal and would be disclosed at the same point in a relationship where you were comfortable telling someone intimate life details like awkward sexual experiences, total number of sexual partners, life altering episodes of fecal incontinence (as in a pool, school or restaurant had to be shut down and you moved away afterwards), any prescription medication you are taking or past medical history. Some people, even those who are married, never get to the point where any of those conversations come up in their lifetimes, and that's ok. Less can definitely be more. Do we really need to KNOW everything about each other's most intimate personal habits? In other words, if it comes up, it comes up. Don't hide it, but don't offer it randomly either. If it comes up, discuss it normally, because it is normal, for you. Unless it's contagious or illegal I don't feel any of these things are part of normal disclosure. I guess as a woman my opinion is different because we're used to hiding our "feminine products" for life? Do you feel the need to tell a partner if you have a preference for pads vs tampons when you have your period? Exactly!
We're adults and if we have external fluid challenges, or urinary incontinence, we wear pads or disposable undergarments. Presentation and correct terminology is everything. You are in control of perception. To me, referring to "diapers" or "pee" would only be appropriate when discussing babies, not adults.
The only exception to my personal opinion is if you're into urine or infantilism sexually, as in a fetish type of nature. Then yes, you should mention that. Not judging but wanted to mention it because this site/forum is definitely not a place for that.