Installing car seat

When should we install baby's car seat? We live 2 hours from the hospital. I'm 36 weeks. I want to install it now/ but I can't do it myself .... Gotta convince hubby we need to get it in there ! 
update: thanks all! Convinced hubby to put it in today! Like someone else said- it will be good for our 4 year old to get used to it as well!