What are some tips for a cellist trying to learn vibrato violin?

Hi there! I'm a conservatory cellist (hopefully right near professional level, I hope!), and lately I've been trying to get into some violin playing for fun when I have free time. My one technical problem I've encountered is with regards to vibrato - I don't get how you do it at all on here!

It's very natural to me on cello, where we kind of bound/rebound the forearm up and down relative to the fingerboard as if we're dribbling a basketball with the side of our wrist, but I know that doesn't apply to violin whatsoever. I've been told that the motion is primarily finger-based, straight on the string, and goes flat rather than sharp like ours - but in my experience, it feels like I genuinely don't have the muscles to make my finger or my wrist bend that way any faster than once or twice in an entire second. None of the advice I've been given seems to help with this, since they just say "start extremely slowly", and I still can't understand what muscle groups are being activated that can twitch as quickly as a real performance vibrato demands. I understand that slow practice is still needed to start, but whatever I'm doing just can't be done any more quickly no matter how hard I try!

If you have any other ways of explaining it, physical analogies, or even some different oddball techniques that are accepted out there, I'd be glad to hear about them. Thank you so much!