Adding on to what specialmom said about pushing against the walls, etc. There is also something called joint compression. It's often paired with a brushing technique but you can do the joint compressions without the brushing whereas if you use brushing you have fo do the joint compressions.
Ask your daughter's speech therapist about them and look them up. I do these on my son when he gets unruly. As specialmom said make sure you tell her "no hitting" and maybe after she's calmed down enough that she's not fighting you can try them. Or regconize the signs before she gets to the hitting stage and use it as an intervention.
She is taking ot pt and st. Thank you!
Hi there and welcome. Well, first, know this. Kids without autism will resort to hitting at age 3 when frustrated, angry or upset. We as parents then guide them to other ways of expressing herself. Not the "I'm having a baby route" as that is pretty meaningless to a 3 year old, ANY three year old. And a child on the autistic spectrum especially as one of the characteristics of autism can be a lack of empathy or ability to walk in someone else's shoes.
So, instead, look to this as an opportunity to teach her better ways to handle her emotions and cope as these are life long skills. It is a bit harder when a child is on the spectrum but still should be worked on. I have a sensory child (not autistic but symptoms of it that are actually his sensory integration disorder and developmental delay) and took the approach that he would learn appropriate boundaries. Period. Hitting was not allowed. I did have consequences for hitting. I also had alternatives to letting out the frustration that we offered.
So, I would say "no hitting" but offer her something else she can do. Have her use paint and make hand prints on a piece of paper and hang it at eye level. She can then go to her 'helping' hands and push against them as hard as she can. This action actually slows the nervous system (pushing against the wall) and will help her calm down. She can go to a quiet spot/cool down spot that you don't bother her in (an enclosed place is good for this such as a small pop up tent, corner with pillows behind a chair, under a table, etc.), she can open and close her hands firmly, she can use her words, etc.
Therapy will be wonderful. Trust me . . . they are good at helping a family overcome situations like this. What kind of therapy are you starting? We do occupational therapy and the behavioral modification portion is really excellent. We were told that undesirable behavior of a child should not be tolerated whether they have a developmental issue or not We took that approach and have helped our son become more main stream that way. good luck