new usedcommand[MAX_PLAYERS];

usedcommand[playerid] =0;

usedcommand[playerid] =0;

usedcommand[playerid] =10; // 10 seconds?

if(usedcommand[playerid]) return SendClientMessage(playerid,COLOR,"Plz Wait");

SetTimer("loltimer",1000,1);

public loltimer()
{
    for(new i = 0; i < MAX_PLAYERS; i++)
    {
        if(usedcommand[i] > 0)
        {
            usedcommand[i] --;
        }
    }
}

public OnPlayerCommandText(playerid, cmdtext[])
{
  if(strcmp("/command", cmdtext, true, 9) == 0)
  {
    if(GetPVarInt(playerid,"WAITBEFOREUSINGITAGAIN")>GetTickCount())return SendClientMessage(playerid,Colour,"ERROR : You must wait before using a command");
    SetPVarInt(playerid,"WAITBEFOREUSINGITAGAIN",GetTickCount()+5000); // 1000 = 1 secs
    // Put some codes here
  }
  return 1;
}