Earlier quoted context omitted.
I've contributed significant changes in my first 3 months at most jobs. Lack of fit (eg with your manager) can become too much at 5 months.
Surely this is the baseline? If you hadn't contributed significant changes in the first three months and I was your line manager I probably would have failed your probation. I wouldn't expect you to be at maximum productivity by this point but I would be expecting you to make substantive contributions appropriate to your skill level and experience within this time.
At 2nd job it took 5 months until the first commit. At my 3rd like 4 months.
Getting up to speed and not being a net time sink for the coworkers, like 8 months on my 2nd job even though I did kinda the same thing in my first job. About 5 months at my third job.
This also make me have a hard time understanding how job hoppers are valued at all.
But reading your comment I realize some companies work completely differently.