It sounds like you might be having two separate problems, one being that your code isn’t sending the correct bytes to control the servos, and one being intermittent startup pulses making your servos twitch.
What bytes are you sending from your program, or could you post your code? If you unplug all of your servos and send commands from your program, what do the servo controller LEDs do? If you don’t send any commands to your servo controller, do your servos still move erratically?
You might want to take a look at this thread. Specifically, are your servos behaving like the servos in this video? If that looks like your problem, try adding 4.7Kohm pull-down resistors between the servo signal line and ground, then take a fresh look at your code.
-Adam