When I introduced my mini-lop bun to my then 3 cats, I did it when he was just a baby; only a few weeks old!
I held him in my hands & let them sniff at him. Cats are natural predators & Buns are natural prey; so I knew I was getting into some iffy territory here!
My bun was a house bun, he had free-roam during the day AFTER he got to his mature size. That didn't take long! I kept him in the cage during the day while I was gone, and I'd get him out at night, hold him & let the cats sniff him & get used to him; during the evenings.
Once my bun got to be his full size (8 pounds) I really didn't have any worries. The cats didn't bother him; they played pretty well together, actually. Occasionally I'd catch Zorro licking on Mr. Kickers, or gently biting him; but my bun would just sit there and seem to enjoy it. Zorro never, ever drew blood or harmed him!
They got along wonderfully. Mr. Kickers died when he was only 2 yrs old to a GI blockage & the cats really missed the little bugger.
Good luck with your introductions!