This really isn’t the optimal starter plug for DWC.. I’m you can get it to work tho.
If you’re gonna try it in those peat pellets, I wait til whatever I’m using (rockwool) has roots protruding from it so that it won’t be long until the roots can hit the DWC water.
I’m not sure I know what you mean by keep them from drowning but you wanna fill up that net cup... you want the water near the bottom of the net cup at first so the roots can find it.. after you have substantial roots, you can let that water level go down a bit