barrels broken both hammers cocked  then close the barrels before mounting the gun and swinging through, same as i do with my more modern guns.
I figure by doing it this way when i am cocking the hammers i am doing so with the barrels open so there is no way for an accidental discharge.
Cocking at the shot i am not a fan of. If you walk with barrels closed and the muzzles pointing up then cocking the hammer ruins my tracking on to the bird as i have small hands i cant easily reach the hammers from the grip. But i suppose its not dangerous in any way.
If you walk with the barrels open then cock and close its going to slow you down so much and if you barrels are open you may as well be cocked as it can't go off with the barrels open.
 If you do it the other way around closing the gun then cocking in my opinion that's even worse because you then have a closed gun and your trying to cock both hammers and get onto the bird quickly, seems like a recipe for accidental discharge.
I carry barrels open both hammers cocked then close and swing up through the bird, then the only time the gun is live is when the muzzles are already pointing at the sky. Issue with my way is that on some of my hammer guns they won't open once closed and cocked so occasionally you close and come up on a bird and don't take a shot, and to open the gun again you have to de cock the hammers which can be a pain if your hands are cold. In such a circumstance i generally just rest the gun on my hip with muzzles raised to the sky.
I know in the US you use pointers a lot which changes things a bit because you can anticipate the flush more.