He should be old enough to be okay overnight. If he has 2- 3 potty breaks while you are at work, that would be great.
My boys are both pad and outdoor trained. My youngest was originally 100% outdoor trained, and I think he piddles often on the pad just because he can. He would be fine if we took the pads away. He does have the urge to pee when he is excited, so we would have to make trips outdoors every time the doorbell rang or we play fetch.
When you do make the change to 100% outdoors, take the pads away completely. If the pads come and go, it will confuse your pup.
Good luck!