Autism ?

I have a 9 month old and I’m not sure if it’s to early to tell but I’ll be mentioning to our pediatrician next appointment. I have a cousin that has a son with autism but it runs in her husbands side of the family. She told me they had told her to look for signs like banging of the head or rocking head back and forth, opening and closing hands over and over and so much more but could I just be worrying to much? I have twins so I see that one of my kids is a bit behind. And well some of the things she told me to look out so my son does the exact things. He’s constantly rocking his head back & forth or sometimes he has moments where he wants to hit his head on things. He also does the opening and closing his fist a lot and besides from the he still doesn’t have strength to hold himself up with support, he’s still a bit wobbly like a 4 month old. Idk if I’m just worrying to much but could it still be to early ?