+atk-def Nino

Nino never has a problem of doing damage thanks to Blade tome, so unless you really need a green mage for your team, or really like Nino, I recommend waiting.

An atk boon Nino is fine, you can never have enough damage. And 36 spd is not that bad. Besides, you're going to use Life and Death anyway and Fury is an option if you want more SPD. You can wait if you want but, I think you're fine.

I would recomend promoting that one since +atk -def is quite good already, if you get a +spd one you can just merge. Nino is one of the best heroes in the game, it would be a waste not using her while you can, 20k feathers isnt that much in the long run. I would also recomend fury 3 over LaD, since you can tank any reinhardt with it, even with QP moonbow, while the LaD one dies most of the time.