amount of perlite and coir in your medium makes it lighter,able to get more air to roots and well nutrient uptake.considering you havent mentioned which bottles you have but I would start giving right at the end of week 1,with Sensi Grow and something like Voodoo Juice.Later you can add ferts like sensizyme,sensi bloom,big bud,carboload etc.Dont follow bottle instructions or youll get your seedling burnt.I would start with 1 ml/lt.you can always add some calcium and magnesium to your feeding as coco lacks them. 250-500ml water is enough,no need to look for a runoff for now.when you think roots achieved a larger area in soil,increase amount of water.Mixing perlite and coco in to your medium will let you water more often than %100 soil so they have a great chance to kick start.good luck mate