I don't feed at all for the first month. I use straight orchiata and keep damp all the time. I just wet with ro and add various root hormones feeding with kelpmax at the appropriate strengths and intervals. I then begin to feed but extremely lightly at around 5ppm N every other watering. As my seedlings are on a heatmat, I water every 2 days or so. I wont increase the strength until I see strong root development.
Gary
UK