yea, during flowering they dont grow out from the tip anymore, so topping isnt needed.
if it was stretching too tall you could have tied it down
if you pinch the tops during veg, it splits into two smaller stalks from that point upwards, and so on
its not a good idea in flower. you will still get a good bud there but it might be a couple different shoots...sometimes ends up with a cool looking bud though
the plants will stop stretching in about a week. they always double or tripple in sixe the first few weeks then just start fattening. you should be close to the end of that stage