If adding vibrato causes you to compromise your fundamentals (i.e. left-hand position), it may be too soon. I’ve only been playing about 18 months, and I recently noticed that adding vibrato was causing me to collapse my left hand and lose the nice “arch” of my fingers. I’m finding it easier to do nice vibrato with my fingers lower, but I don’t want to fall back on that as a crutch.
I’m going to take a break from vibrato for a while until I can do it properly, with my hand and fingers at the right height above the fingerboard. I’ll add it back in as soon as I can without building bad habits.
Hopefully Michael will chime in to let us know if that’s the right approach!