When yo increase light intensity

Been I've no idea what lights you are using. And your girls aren't stretching tells me your light is at the strength it needs to be. 500-700ppfd should be enough for your entire veg. After she hits pre flower then turn them lights up. But as for now you can get her done on, this is just a guess 50-70% of your lights strength. You wanna keep the 100% of pre flower and so on . Good growing