Any advice for training a lhasa apso puppy to use the toilet outdoors?

My puppy had his 2nd vaccination a week ago, so he's ready to walk outside on his own tomorrow (woohoo!). He's doing really well using puppy pads when he goes in the house, so I'm not sure whether this will make it more difficult to toilet train him outside. Does anyone have advice on how to make the transition a bit easier?