Hello,
I'm not sure there is a need to add much more but little things :
- I wouldn't recommend pads : you save your floor, but the training will take longer as they could learn that doing inside is OK
- I would go for the grass box, or even sandbox on the balcony : a special place outside. Having grass of sand can help to recognize the feeling when outside
If he knows to do on the grass on the balcony, the grass outside will feel "familiar"
- signs management is important : we had the chance to had Loki while he was almost clean : most of the accidents were because of us not taking enough attention of the sign. If we would have been more careful, we could avoid most of them if not all
- time : it's the kind of training that will become better with just time, as the bladder will grow bigger, and they would be able to restrain themselves longer
and of course, congrats for the pup !