x2. Impossible to give advice without seeing what you're working with. Or else generally we're going to assume you have limited space and a bare, boring run, but sometimes folks surprise me with a really good set up, but their adult birds are just simply nasty to babies.That said integration takes a long time sometimes.
It's about space and resources.
Can you post pics of your set up so we can better help problem solve?
I begin integration around 2 weeks, sometimes a little earlier depending on how things look, so much different than how others approach integration where they want the birds much older.