Can anyone tell me how early you can add nutrients?

these are all Nitro Lemon Haze. Week 2 veg. Some of the leaves are looking limp and a little yellow. try to determine if there are early issues.

all still being sprayed on the surface with ph balanced water. Light is about 30 inches from surface. All in light warrior seed starter soil from fox farm. nothing added to soil except the water. Temp ave 75 degrees f and humidity hovering around 65 percent. (Humidifier in tent on fully)