600w RDWC grow

So I'm new to hydroponics and I was wondering how u start from seeds?

After germinating do the seeds go in soil till they are about the size of a clone or right into the net pots.

I fill the net pots with hydroton then place the seedlings right into the net pots...
some say this, some say that, I've never had a problem ....although I'd let them get a couple 3-4 sets of leaves 1st

How long could I keep seedlings in soil before moving them to the rwdc system? I have everything I need to start in soil so I'm thinking of starting soon and building the rwdc system as they grow.