Do you think Harry gets his good parenting skills from the Weasleys?
Harry knows what NOT to be in a parent, but all in all he doesn't have that much experience with good parenting, especially with younger kids.
But then Victoire is born and he sees how patient Bill is with that toddler when she's throwing a tantrum. How Mr Weasley bends down to explain something to Victoire even when his knees object and she's been loud all afternoon. He'll show her with eternal patience again and again until she understands.
And then others get kids and it's much the same. There aren't violent threats, there is patience and understanding and so much love.
And so when little Jamesy is born, Harry has been absorbing it all , he knows exactly what kind of dad he wants to be. It'll take more work, and learning, but he knows.
This is, yes, a big part of Harry learning the alternates to what he already knows is not how he wants to be. Don’t discount Andromeda Tonks though; he is committed to helping raise Teddy Lupin because he knows what it’s like to be an orphan, both parents dead. And Andromeda has experience with this, particularly with a metamorphus.
The point is, along with his determination to not do things like the Dursleys did, Harry has a wealth of good examples to learn from. Both Arthur & Molly Weasley, then Andromeda. Also Bill & Fleur. Other Weasley’s. And finally Ginny, who is going to recognize Harry stressing about this, and call him on it. And make sure he knows he’s got that wealth of backup.
