Canna grow chart help

[BakerT]

G'day I'm been growing in soil and since I started but for the ease of a couple of DWC bucket system I'm giving hydroponics a ago.
I'm using Canna Aqua and I'm very happy the growth I seen in the last 2 days since they got there first full strength drink is amazing compared to soil
But whan do I start feeding the flower A & B
Is it as soon a turn change the light back or do I follow the Canna grow chart and wait till I c tips starting to form?
Thanks

 

[TorturedSoul]

Cannabis uses a good bit of nitrogen during the stretch phase.