Help I don't know what to do anymore.

My small child has been in absolute terror at daycare. For the last few months, we have continuously worked on mechanisms and tools to help him when he's angry and frustrated so that he's not lashing out at friends and teachers. We have found that when he's in a calm environment, and we talk to him about those things, he knows exactly what to do. He can tell you what he's supposed to do - he knows he's supposed to ask people to give him space, that he's supposed to walk away or talk to anyone teacher, that he can go to the quiet corner to count to 4 or go read a book. But in the moment when it's happening, everything shuts down, and he just Doesn't listen. He is hitting and kicking his teachers and his friends. He is climbing on furniture and jumping off of it after repeatedly being told not to and that it's not safe. I had to have a conversation with the daycare director just a week ago because they were concerned about him. And now I'm on my way to go pick him up because they don't want him at school today because he can't keep his hands to himself. We just had a visit with his pediatrician YESTERDAY who referred us to a therapy center and provided early assessmentforms for ADHD- but it took 3 months just for the behavior visit we had yesterday. It will likely take 2-3 more months just to get him in therapy. I'm running out of ideas! My boy is SO SMART and excelling academically beyond his classmates, but emotionally, he's struggling so much. I debated taking him out of daycare and finding a part time nanny or something - but he's been there since 7 months old and all his friends are there. What do I do?