Gnome3 has a major flaw, theres no easy way to run a command that lacks a .desktop file (meaning something that does not exist in your menus can not be run at startup. Here comes the best GUI solution to that:
This is a simple GUI for running commands at startup (Login is more correct). The instructions on the GIT site is very good so I’ll leave you with that.
Note: The scripts / apps does not need to be in the $PATH, just add the full path.