Current-bar-is-at-least-3-bars-later-than-the-entry-bar

CODE:
        public override void Execute(BarHistory bars, int idx)
        {
            if (!HasOpenPosition(bars, PositionType.Long))
            {
                //code your buy conditions here
            }
            else
            {
            Position pos = LastPosition;
            if (idx - pos.EntryBar + 1 > 3)
            {
               PlaceTrade(bars, TransactionType.Sell, OrderType.Market);
            }
            }
        }