That’s a more normal approach; you’re ALWAYS vested in your own contributions (it’s your money, after all) but legally you have to be vested in the company portion within a certain time. I seem to recall the law changing a few years ago, to mandate either 100% vesting at 5 years, or a step vesting starting at 3 and done by 7 years. An example of the latter is that at 3 years, you’re 20% vested, at 4, 40%, at 5, 60% etc.
Though my husband is nominally vested in his company’s contributions immediately; I think they may have changed it shortly after he joined, for people who joined later.
So, immediate vesting in the company’s portion is not the norm, but not unheard-of either.
What is interesting is companies that don’t let you contribute even your own money, until after you’ve been there for a while. 20+ years ago, when I joined my company, you could only start contributing on a specific date after you’d been there for a full year. So I joined in October 1988, my anniversary was October 1989, but I couldn’t contribute until May 1990.