I just water in a circle around the root riot cube I use and every day move a little farther out. An ounce or two to start then build on that. Around day 15 I start with about a 1/2 liter a day. It is more of a feel thing to be honest. If you pour a liter a day on a seedling you can over water it. The more perlite you use the less like you are to over water. I started using 60 40 and when they get big it is a three times a day chore to water to keep the pot wet. I now am more like 85 15 just to get the drainage. Just go slow and steady. Now you can experiment a little I know people on here that never water once a day every day or three. Honestly depends on what your going for. I have tried the every other day method and the plants are bigger watering every day. Due to getting more oxygen and nutes. That is the great thing about coco it is pretty adaptable and long as you follow a few simple rules you can do it the best way you see fit. I know
@jingo does a different watering schedule than I do and he grows monsters. Once your deep into flower I don't think you can over water. I use the weight of pot to determine when to up the water. I have had some plants get to 2-3 liters a day. Now take into consideration that is with a little run off. Sorry about the ramble that was meant to be a one or two sentence answer.