Post #42: _enter_tree() and _ready()
According to the Godot docs:
Intro
Two functions allow you to initialize and get nodes besides the class's constructor:
_enter_tree()and_ready().
You are able to override both of these functions in order to define behavior as you best see fit.
_enter_tree()
_enter_tree() is called on a node when the node enters the scene tree.
_ready()
Called once in a node's lifetime, after enter_tree().
_ready()ensures that all children have entered the scene tree first, so you can safely callget_node()on them.
Check out the docs here!