I’ve upgraded from my Steam to my VRChat account and yet I’m still visitor. I’ve played for a day longer than my friend and he upgraded and he’s User. How can I get to User when I’ve already upgraded?
It’s different for everyone. Depends on friends, people you’re around, and such.
You’ll get it eventually 
Linking your steam and VRChat account are not guaranteed ways to up your trust rank.
If it’s absolutely necessary, paying for one month of VRC Plus will guaranteed get you to New User rank. Otherwise, just keep playing and you’ll rank up eventually.