So, hi. I'm pretty new to Godot! And I'm trying to make a 3D space simulation game! I just need help on trying to implement 3D asteroids that randomly spawn :) Advanced thanks for all your support!
You could just have a spatial node with a timer added as a child and with a script on it that will create instances of your asteroid scene and add them as children to the spatial on timer timeout up to n(amount of children).