Hi I’m using 70% coco and 30% perlite for My pla...

I am a experienced coco grower. Select my answer and I will walk through the grow with you. It won't let me type what I need to say.

Both coco and perlite have zero nutrients, so yes, you will have to feed.

and to be clear, you add fertilizer EVERY time you irrigate! lol .. i'm not usually so directlay cofrontational but sometimes bad information is given in the answers. It is overtly wrong to suggest otherwise. not doing so would defeat the whole purpose and benefit of a soilless medium. 1,3 to 1,5 EC will not burn a plant unless something is crazy far off and out of balance (ratio of nutes is just as important as overall concentrations. 120+ ppm N 60+ ppm P 190+ ppm K 100+ Ca 75+ Mg less than 110 S. thats somewhere near a 1,3 ec with a good balance of nutes. you can input percents off labels at manic botanix nutrient ppm calculator. or the npk ratios come out to roughly 8-8-15. In flower you may need to drop N 10-20 ppm. In vege some plants may want as much as 140ppm N. This is only meant as an excellent starting point. this formula will work for soilles or hydo. extra co2 and a highly controled environment can probably push 10-20% higher in concentration, but maintain the same ratios.

given the typical EC concentration of soilless fertilizer, 1,3-1,5 EC, you can feed right away. the only concern with seedlings is not to drip on them. you'll burn the growth tip off, lol. the first 5-7 days probably don't need it, but doesn't hurt as long as a little careful about the seedling and what can get on it. i get much faster starting growth rates if i fertilize from day one in a soilless medium. it has zero nutes. if oyu use somethign like promix, it comes with a light 1EC charge or so. soil has nutrients, so you can wait. coco does not. you need to provide 100% at all times. stick to a well-balanced 1,3 to 1,5 EC concentration and water until you get 10% runoff waste, religiously. You may need to tweak your formula, but that 10% runoff is key to avoiding problems when you have a good formula worked out. This will be a good ballpark to start. it shuold be easily to react to any symptos you see and quickly adjust formula... with small adjustments, a 10% runoff will reset teh substrate concentration with a single fertigation. larger changes you can give a little extra runoff and maybe it takes 2 irrigations before it's fully changed over, no big deal. it's fast.. not as fast as changing a hydro reservoier, but it happens almost immediately of only doing fine-tuning adjustments to formula. unlike soil.

Yes, your plants will need food right away. Good luck with your grow and remember don't add nutrients every time you water or you will have nutrient burn.