[MetalMan]

You can't know how long it will take to balance a pack because it is very difficult to find out how much capacity the balancer has to drain in order to get a cell/cells to the same voltage as the lowest one.
It would be faster (and safer) if you balance during charging because the balancer can operate the whole time. Whereas if you plug it in after the charge, it starts the balancing right then and will add extra time.