Yea seems like you're stepping lightly. What i would do if your going to use FFOF which Im using... Id used the Happy Frog for the rest of the veg stage. That way you are existing out of the seed starter into the medium strength soil mix and not directly into the full strength. Then as you implement your ONCE A WEEK SAME DAY FEED and your ONCE A WEEK WATER, you will have NO problems. Dont confuse one water a week as just that. When you feed once a week and water once a week youre actually watering twice. Most New Growers (respectfully) dont realize that they are over watering by watering every other day. This is how root rot and salt build ups abound. This kind of schedule never fails.
actually if you are in air pots or fabric pots that are smaller than 5 gallons, they need watered every other day many times, especially during flower.
it really depends on the environmental factors such as heat, air circulation, humidity, if he adds extra perlite (suggested but not absolutely needed, would follow the previous advice of 1 tablespoon of dolomite lime per gallon of medium), etc.
You can't just set a schedule for watering, you must know the plants well enough to know what they need when they need it. Not give them what you want when you feel like it.