[Pooh7]

What will happen if I use KillTimer for timer what is not started?

Example:

pawn Code:

new timer[100];
public OnPlayerConnect(playerid)
{
    KillTimer(timer[playerid]);
    return 1;
}

[Joe Staff]

What you're actually doing is deleting the Timer with the ID of 0 (since you haven't set the value of your variable), so unless Timer ID 0 exists, you're doing nothing.