Gapup and gap down stocks

For Intraday gapup and gap down
1 what percentage of gapup and gap down should be need to be considered for intraday
2 which candle high or low brakeout should be considered first candle or second or third candle high low considered for buy and sell

Each days market sentiments are different, Instead of using a quantifiable % to trade Opening gaps, monitoring the Top 5 UP and DOWN gaps during the pre-open session might yield better results.

Ideally, For Opening Gap Intraday Breakout Trading, Which ever time-frame you choose to trade on, say 1min, 3min, 5min wait for a retracement of not less than 50% of the days current range and then trade the breakout in the direction of the gap.