i usually don't let them start growing vertically until i flip to 12/12, so it's not 'too much'.
Some big stretchers need a little training a week or so into flower, some may need to start going vertically before flower -- in order to maintain a level canopy.
you are fine.. just spread it out as it grows vertically to fill the empty space.
The key is to have an end goal. If you want 2.5-3 colas per sq ft, make it happen themost efficient way possible.. .easy peasy when you work backward from an end-goal. ther is no uncertainty. you simply make sure enough colas will fill the sapce and let it go.