I do not have any block skip switch on my machine, so I cannot test its function. So, somebody may please clarify my doubt. Thanks for your time.

The manual says:
"Optional block skip operation is processed when blocks are read from memory or tape into a buffer. Even if a switch is set to on after blocks are read into a buffer, the blocks already read are not ignored"

What exactly it means?

Does it mean that we have to set this switch on before OSRHing (i.e., displaying on the program screen) the program?

Or, can we set this switch on even during the execution of the program, any time before the execution has not reached the affected block (i.e., before the affected block is not pre-read)?