I prefer to use price action signals like the hammer (with confirmation and pullback) or bullish engulfing pattern as an entry trigger for this pattern. (fxdayjob.com)
In technical analysis, when you hear the term bullish engulfing pattern or bearish engulfing pattern, what they're talking about is a candlestick chart — usually a daily — where today's low price and high price are below and above the high and low of the previous day. (thereformedbroker.com)