Nougat downloaded but now not in notifications
If you don't want to sideload it I believe you will get it with the next OTA wave. Also, I remember people were forcing OTA with Google Service Framework disabled back when 5.0 came out, but I havent tried it so I really don't know if that works or not. Here are the steps if you want to give it a try:


Find Google Service Framework in the Apps section of your Settings menu
Force stop it.
Try the System Update option now.