Somewhere between "girlfriend" and "wife" it makes sense to share. One defensible milestone would be after "girlfriend" becomes "fiancee." Or maybe in the weeks leading up to an engagement decision: at least before you marry, and perhaps before you decide to get engaged, it would be good to understand how compatible the two of you are with things financial. Money arguments are, unfortunately, a significant contributor to divorce. Better to have those discussions beforehand.... Good luck!
I think that's a reasonable point to really dig into finances - engagement being a "Ok, we intend to get married, barring any major problems, let's really dig in" period, as far as I'm concerned.
Why are so many people recommending only telling financial details before marriage? This is the same forum that reams people for not talking finances before marriage! Yes, I agree if they've been together like 2 months it's not a great idea to open the spreadsheets. But beyond a few dates, shouldn't you at least know broad swaths of your partner's finances? And before even *considering* engagement, I would hope you'd have a pretty good idea of their finances, and they of yours!
Perplexing change to advice here from the usual.
It depends, but my now-wife had no idea of the details of my finances until we were engaged, beyond basics. I actually went out of my way to not make financial details too evident when I was meeting people, because I had no real interest in anyone who was excessively interested in my finances... several friends demonstrated that no matter what you earn, your wife can out-spend it (even if they were pretty clamped down on stuff).
My wife knew I was financially stable, and I knew she could pinch a penny hard enough to squeeze blood out (she was living alone on a teacher's salary, paying down student loans, driving an inexpensive car, etc). That was sufficient.
As we moved towards getting engaged, I'd say we had discussions on finances, but nothing particularly detailed. I did know the student loan debt she was paying (not that much), and her car loan (her parents were more or less horrified at the car she was driving when they came to visit and made a very substantial payment on "not a rolling wreck" for her, with the remainder of some of her college savings or something like that), but we didn't really merge finances until we were married. She had her own accounts, and we had a shared cup of money for groceries (cash), but were still separate up until we got married.
At that point, I paid off her (now our) debts and we've gone forward merged, though that's pretty easy since she stays at home. I make the money, she spends it far more efficiently than I would.
But, no, I don't see any advantages of sharing details early in dating, especially not if you're very well off. I had no interest in someone liking me for my cash, and tended to show up on a motorcycle places for dates (which, to be fair, was because I showed up everywhere on a motorcycle).