It sounds like you’re doing High Frequency-Low Volume fertigation?
How ever frequent is needed to keep the coco fully saturated. Best practice is to keep the coco between 90-100% saturated. So each feeding event should take place when coco has lost 10% of the water it can hold. You could assume about half of the container volume is water when fully saturated. So in a 5gal pot, 2.5gal is water and 10% of 2.5gal is 1 quart needed of a nutrient solution to get the coco back to 100%. It should be enough so that however much you put in, you should get 10-20% of it as runoff, for 1qt that’s about 1/2-3/4 of a cup. Feeding 3-5x daily is about average for that type of feeding but it’s really gonna depend on what the plant is using. But remember…things don’t have to be perfect. You’ll end up with more mistakes trying to focus on perfection.
Smart move going ahead and starting with auto watering. Hand feeding even just a couple plants like that gets old really fast. I was doing it and I would end up letting the coco get really dry because I didn’t wanna get up to feed. Letting it dry out is the one thing you don’t want it to do.