Ruth, I am not completely clear about your request: what is your role in the situation, and why do you want to work with Holacracy there?
I am with Ruben here: If there is someone who is passionate about it in the right position (e.g. a founder), and ideally competent in teaching / coaching the team, then Holacracy can be relatively easy for people to learn right from the start - and not a "huge mental shift" that comes "on top of" doing the ordinary work required.
If you do not have such a person, it might be a bad idea to start off with Holacracy. It might be worth working more conventionally first until some operations stabilise, and then introduce what is needed.