I just renewed my car registration using this new system that they started March 2015. It think its better than having 2 stickers on the windshield. So just have your safety inspection done before your Vehicle Registration expires. Usually 90 days before your sticker expires would give you a lot of time.
When you do online renewal it does check it automatically in the state database to verify if your car had passed the safety inspection. Your car insurance coverage is verified online as well.
My safety inspection doesn’t expire until 8 months later so the safety inspection validation was approved.
Go to this website for more info. http://twostepsonesticker.com/