You don't even have to do it before you have children. You can wait until they are six or so and have the autonomy to pick what they want to watch (under your guidance). For children younger than that, you pick what they watch and when they watch it. Every time.

Do start hoarding the better shows and series you know.

I just threw infuse logged in as "kids" to Jellyfin which has curated kids stuff - and it's all tied to a custom home assistant timer profile that turns jellyfin access off at a particular time; there's a "door lock" in HomeKit that can be used to extent TV time past the normal cutoff if a parent decides, but since it's a door lock "hey Siri" can lock it, but not unlock it.