Almost 3 with SPD and completely misunderstood

Currently my biggest stuggle is Deven soon to be 3 in mid-april and have went threw more daycares then i can count. I try to share as much info as we get from out therapist and make them overly aware of the kind of care Deven needs Im a single parent who works full time. Deven was Diagnosed with SPD about 10 weeks ago. My biggest struggle is that he is overly aggressive with other children and get SOO SOO SOO anxious when hes around more than 1-2 children. The littlest thing puts him in freak out mode of hitting / biting/ pushing pulling hair. He shows great empathy after he has hurt the other children but does it repeatedly over and over again all day long.

In discussion with his therapist yesterday we decided making "deven box" a place to go when he starts getting close to that place of anxiety and out of control.. but and ideas on what to do when he hits ect... what can i do to express to him that its wrong to hurt ppl so he understands? He says hes sorry and shows empathy but keeps doing it over and over and over... Time outs are en-effective and a completely joke. i stopped doing them bc he would just laugh at me... now he cries and says" im sorry no hitting no biting, no pushing and ill be nice to my friends" still over and over and over again. PLEASE HELP ME!!!