The mixing is fine - though you may need to adjust based on how the plant grows -- time will tell. Every garden has slightly different variables that will impact this.
You aren't watering with good habits. Stop trying to decide how much to give. you'll only end up with buildup or worse in your substrate. Just as above, numerous variables, how it is constituted, will impact how much water yo need to give along with how long you wait between irrigations.
So, you water until the entire thing is wet - a little runoff is fine but you can minimize that waste, but always make sure entire substrate gets wet. Then, let top 1" dry (or so). Repeat. Don't stray from that. You will learn how much water you need in hindsight. If you water at same dryback / loss of weight, then it will require a similar volume each time so you don't waste mixed fertilzer etc.
you don't make these choices. the water capacity of the substrate and the amount of dryback you have determines how much water is needed. if you buy the same products or make your substrate teh same way, you'll know the volume in the future too, but first you have to learn it from doing.