Hello, James.
Probably the simplest way to start your script with a button press is to add a WHILE loop to the beginning that exits when the button is pressed. You can find some code for doing this in my post here. Please note that the code there is for a button on channel 5; you can change the 5 to a 0 to make it work for your button on channel 0.
If you put the WHILE loop before your BEGIN/REPEAT loop, the sequence will repeat forever once the button is pressed. If you want the sequence to wait for the button every cycle, you can put the WHILE loop inside of your current BEGIN/REPEAT loop.
Brandon