since coco literally has nothing in it, now you have coco with 400 ppm of calmg in it leaching off. make up your seedling solution 400ppm mild nutes, run it through first, plant and off you go. Keep it moist and not overly wet all the time you do not let coco get "dry". It's a life line to those of us who tend to be heavy waterers and like seeing it moist.  You are providing all the nutrients and pH should be your target pH. 

You can adjust watering frequency by the amount of perlite added to your mix. if  you want to stretch it out to once a day you want less perlite, constant drip or in my case bottom feed, 50% perlite is what you want.

hope my ramblings will be useful