When should partners start sharing finances? Not splitting - actual "my money is your money".

*if titles could be edited, would for sure change this to read "when do you consider sharing" or similar rather than "should". Lesson learned, sorry to those it rubbed the wrong way.

I just saw an upvoted comment of someone vehemently insisting that if a couple is living together, say by the two year mark, that they should be sharing finances. Literally "their money is my money". Additional context for the post would be that it was about a m/f couple, and the man had a career while the woman was a student. (The man also kind of sucked, but that's wandering off topic.)

Now, the idea that finances should be completely shared at that stage of a dating relationship was very surprising to me, even when living together. If it was my relationship and I was the high earner, I really don't think I would be comfortable with that arrangement.

But anyway, how do you all feel? Is there an expectation on this that I'm out of touch with? Or is it such a nuanced and personal decision that trying to set a standard doesn't make sense anyway?