WaitFor has two ways of working:

Syntax 1: to send a signal
    WAITFOR [/S system [/U user [/P [password]]]] /SI signal

Syntax 2: to wait for a signal
    WAITFOR [/T timeout] signal

Description:
    This tool sends, or waits for, a signal on a system. When /S is not
    specified, the signal will be broadcasted to all the systems in a
    domain. If /S is specified, then the signal will be sent only
    to the specified system.

Parameter List:
    /S     system         Specifies remote system to send signal to.

    /U     [domain\]user  Specifies the user context under which
                          the command should execute.

    /P     [password]     Specifies the password for the given user context.

    /SI                   Sends the signal across the net to waiting machines

    /T     timeout        Number of seconds to wait for signal. Valid range
                          is 1 - 99999. Default is to wait forever for signal.

    signal                The name of the signal to wait for or to send.

    /?                    Displays this help message.

    NOTE: A system can wait for multiple unique signal names.
    The signal name cannot exceed 225 characters and cannot
    contain characters other than a-z, A-Z, 0-9 and ASCII
    characters in the range 128-255.

Examples:
    WAITFOR /?
    WAITFOR SetupReady
    WAITFOR CopyDone /T 100
    WAITFOR /SI SetupReady
    WAITFOR /S system  /U user /P password /SI CopyDone

c:\>ver
Microsoft Windows [Version 10.0.19045.2075]