Which stage is this?

Is that an auto or a photoperiod? As I only see preflowers. If it's a auto shes starting into the transitional period and begins to make the change over into bloom. I wouldn't switch to bloom feed right away. I'd start with a well balanced feeding or a "transition" feeding. If it's a photoperiod.... there are no signs of budsites on your lady... so all those preflowers would tell u is that plant has hit maturity. Unless light hours are reduced close to 12 hours she will continue to veg as a mature plant. Preflowers on photoperiods is just a sign of maturity unless hours are reduced. Because autos flower once the hit maturity automatically... they ARE a sign of the flower transition on autos. Happy growing and stay lit fam.