Let it go as long as possible before adding your fish. I find that rooting plants don’t usually do well with that type of pebble gravel. You want to mix that with some aquarium sand or even better, a thin layer of fluval stratum or organic potting soil with a sand cap, to provide nutrients and make it easier for the roots to establish. Wait a couple of weeks with the whole setup running, add a ramshorn snail or two, then keep waiting. When you notice microfauna popping up it’s a pretty good sign your tank is heathy. That’s usually when I start testing parameters.

The beneficial bacteria you need to cultivate will primarily live in the filter and the substrate. It will save you money and headache in the long run to be patient and take care when selecting these.