We have a 20 gallon in the living room and I made the kids wait almost four weeks before anything went in. I explained it like letting the filter grow good bacteria first. They were impatient but it was worth it. Very little drama since then.
For kid friendly options we liked platties and a small group of neon tetras. One albino cory. We feed lightly and change water every week or two.
If you stay with fake plants for now that is fine. Real plants can help once you are stable but they are a whole other learning curve.
