For seed starting I like to add extra vermiculite to the ProMix.
I like to use 16 to 20 oz white styrofoam cups.
I place the seeds into about 1/4 inch deep holes in the mix. Cover gently and water very carefully, as to not dislodge the seed.
After the seeds pop up out of the ProMix, I wait until they need their first watering and begin with nutes at that time. 1/4 tsp per gallon of water (Jack's Classic all purpose).
I increase the nutes as the plants show me what they need while growing up to be big and strong.