First month after leaving a toxic job and I still feel off

I quit three weeks ago and everyone keeps saying I must feel so relieved. I do, sometimes. But mostly I feel disoriented — like my nervous system hasn't gotten the memo yet. I flinch when my phone buzzes. I still dream about my old boss. I'm glad I left, but recovery isn't instant. I'm learning that leaving was step one, not the finish line. If you've been through this, how long before you started feeling like yourself again?