new
    Timer,
    TimerCount = 0; // Sets the timer count to zero.
CMD:start(playerid,params[])
{
    Timer = SetTimer("YourFunction",5000,true); // Repeats a timer of 5 seconds
    return 1;
}

forward YourFunction();
public YourFunction() // Every 5 seconds....
{
    TimerCount++; // Timer count is added. The Timer will repeat itself until it matched the below if statement.
    if(TimerCount == 5) // If the timer has been repeated five times.
    {
        KillTimer(Timer); // Then kill the timer.
        return 1;
    }
}

new Timer;

forward YourFunction();
public YourFunction() // Every 5 seconds....
{
    // Object Code here
    for(new i = 0; i < MAX_PLAYERS; i++) // Loops through all the players
    {
        
        if(!IsPlayerConnected(i)) // If IsPlayerConnected for all players returns false.
        {
            KillTimer(Timer); // Then kill the timer.
        }
    }
    return 1;
}
public OnPlayerConnect(playerid)
{
    Timer = SetTimer("YourFunction",5000,true); // Repeats a timer of 5 seconds
    return 1;
}

new Timer,PlayerCount;
public OnGameModeInit()
{
    PlayerCount = 0; // Whenever the server is executed, player count will be zero
    return 1;
}
public OnPlayerConnect(playerid)
{
    Timer = SetTimer("YourFunction",5000,true); // Repeats a timer of 5 seconds
    PlayerCount++; // Whenever a player connects player count will inscrease by 1.
    return 1;
}
public OnPlayerDisconnect(playerid)
{
    PlayerCount--; // When a player disconnects player count will decrease by 1.
    return 1;
}
forward YourFunction();
public YourFunction() // Every 5 seconds....
{
    // Object Code here
    if(PlayerCount == 0) // If no players are on then....
    {
        KillTimer(Timer); // kill the timer.
    }
    return 1;
}