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.
I am baffled by this. It has to be so different between fields and companies.
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.
At my last job I had a small bugfix (a one liner but still a bug) committed on my first day, PRed and merged by the end of my second day. That job was the definition of hit the ground running but still. Damn.