In order to set up parental controls on an account, you must get a parental control email from Blizzard. You get a link in that email that you use from that point forward. Fill out this form to get that email.
These are the parental control settings that you can change for your child's account, even if there are no games on it yet. Note: Real ID defaults to off.
Make sure your time zone is set up correctly here, so that any schedules or reports work for you. You can have a play time report sent to the parental email account (that's the smudgey bit). And you can set up limitations for play time for each day and/or week. These play times do not affect the schedule -- only how long your child can play before being cut off.
The schedule defaults to fully restricted if activated. The selections in blue text on the right-hand side are default setups, but they all can be customized for your child.
This one forces a break every two and a half hours.