The easiest way would be for you to move your scripts in the “niryo_one_ros/niryo_one_user_interface/scripts” folder. Then edit “user_interface.py” to import your script and call the needed functions at the end of the __init__ function. This way, your script function(s) will be called at the end of the whole loading.
Or alternative, if your created your own ROS package, you can launch this node by editing “niryo_one_ros/niryo_one_bringup/launch/user_interface.launch” file (http://wiki.ros.org/roslaunch/XML/node).
Let me know if you have problems with those methods