If your supers are full its time to put another on, doesn't really matter to the bees. They need room.
If you want some comb honey, take the full one off and put the empty on bottom.
I find it less work to top super, then when your ready to harvest if the top isn't full, sit it aside till you get the full ones off.
The next super should be put on when 7 out of 10 frames are filled and mostly capped.
It all adds up to your preference.
doak