I am with you!!! My son acts/acted like this too. He used to be one that when you dressed him (before he could do it himself) everything had to be right side first. Right foot, right arm, etc etc etc
He always had to go first to a pervasive level... He had to have everything blue, He NEVER put his shoes on the wrong feet. (One time he did and noticed it in the car... he started FREAKING out like his feet were on fire and I had to pull over--thinking he was hurt-- and get his shoes off and calm him down)
It's like I just said, it's that pervasive level he takes it to. He is still like this. One event can happen and he will totally fixate on it. I am constantly telling him it doesn't matter, forget about it.
A wise Behavorial Therapist once told me that you can't accommodate their rigidity because the real world will not. I can make sure he always gets the blue spoon, but when he's in Kindergarten and kids are grabbing different colored items nobody is going to reserve the blue one for him.
Like other Mamas have said, you have to pick your battles though. There'd be times we'd be running late and I'd let him go first so I wouldn't have to deal w/it. There'd be times I wouldn't want to deal with the struggle and I'd make sure he got the blue one. etc. But.. there have been times I've been the blue pawn on purpose in a game or whatever. He has come a long way and is still very rigid, but not like he once was.
I think there will always be something... we just have to stay one step ahead!!!! Best of Luck!!! Autism is something that can bring a lot of emotions, but I think there is also much joy.