As the mother of a child with Asperger's, one who has difficulty with change but not to the extent of most other Autistic's, I see this as no solution at all.
This decision should also have imput from his doctor.
As far as the calendars go, assign a color to each home. Completely color in the weekends his spends with you and the weekends he's at his mother's house. Keep reminding your son where he'll be going and tell him the time that he'll be going. I find that my son can acclimate much better to the change if he has all the information ahead of time. He's a stickler for times. He needs to know the exact time something will be happening. Without that knowledge, he'll become very antsy.
