For the most part, don't expect coir or peat to have any nutrition at all. Seeds need no nutrition to sprout and grow a little bit. When the plants have grown just beyond their dicot stage, or having their first "true" leaves, then nutrition gradually comes into play, so then maybe you get ready to do the first transplant into, say, cups. Fertilizer should never be needed in growing media.

Depending on your habits, these things may dry out a little too fast compared to other media, so watch that carefully. I flood mine and then drain all loose water (after a dozen seconds or so), but when they're sitting out in the sun (85F/30C today!) I do it twice.