Flowering- you will know this when she starts growing many pistils in the top and the branches inbetween the fan leaves and the main stem.
Nutrients- start at ⅛ indicated potency then climb to ¼ then ½ and after that try giving full dose. Its how i'm doing with veg nutes and stims, i would say do the mix like that and then start with using 200ml mix, then 300ml, 400ml, depends on how she is reacting. You have to be very carefull with nutes.