SYSTEM

I have two questions about resetting a MacBook Pro (early 2011), Sierra system.

1. To reset the logic board, when you hold down the [COMMAND] [OPTION] [SHIFT] and [POWER] keys …should the MacBook in plugged into a power source, or not. Also, how long should you keep the four keys pressed? I have heard everything between 10-seconds and 2-minutes.
2. When resetting the Parameters, how many times should you hear the startup tone before releasing the [COMMAND] [OPTION] [R] and [P] keys? I have heard everything between one and 8 times.