I've never grown in coco. I like my soil to dry in 2-3 days (when the plant has grown into the container. When the container's not grown into, it can take twice as long to dry. That can be tricky to keep it uniformly moist, but not fall into the trap of giving little sips all the time, never letting it dry as much as it should.
I determine when to water by lifting the container. You can keep another container full of medium (never watered) and compare what they feel like when you lift them. Or, you can let your plant reach the "too dry" state, where the leaves start wilting. It can almost look like overwatering, but it's a different kind of drooping which looks more like wilting. Lift the container to know what "too dry" feels like. And then try to get to close to that. It doesn't hurt to do that once, so you know what it feels like. I wouldn't do it to a seedling or flowering plant. It's a stress. But, it's not bad in veg. The leaves will bounce back in 20 minutes after watering. It's a tradeoff. One stress versus continually watering too soon. It's really surprising how light the container can feel (while still not "too dry." It won't feel natural to you. The only way to experience that is to reach the "too dry" condition once.).