Best of luck this round!
You can try this if you want. It works for me when I'm starting plants. Others may disagree/have better methods.
To prevent over watering of young plants, I stick to watering 20% - 30% volume of the container size.
Ex; A beer pong cup holds about 2 cups of water. When I water my plants in those, I give them about 1/2 cup when the planter cup is very light.
You've probably been told/have read about watering to x% runoff. I believe that's where alot of us new growers run into problems in the early stages of plant growth.
Unless you are in the process of adding nutrients - which you don't need to in ff (or any quality soil) that early - there are no excess salts to "flush" out of the soil yet. All you are essentially doing is leaching the provided nutrients (already in the soil) out of the soil.
In fact... If you start in cups, then move to larger pots for veg, then move to final pots, you don't need nutrients until flowering (imo). So 20% - 30% water per volume of container.
I prefer to put the water in a dish and let it soak up from the bottom, but the principle is the same for top watering.
You're soil's provided nutrients will actually deplete at a faster pace watering to runoff which will make you need to start ammending it sooner. Kinda defeats the purpose of buying good soil in the first place lol.