Idealy if I can automate all 3 cameras in sync.
If you want excellent synch you will have to use a simple microcontroller (such as PICAXE) to switch +5V to the USB connector on all cameras, a script is not required.
Synchronised shooting begins when you remove the +5V.
Some people are using nine cameras synchronised with StereoData Maker (SDM).
If you do not use a microcontroller but start the same script in all three cameras, I have no idea what the synch will be after 30 minutes.