lowest

//@version=4
study("My Script", overlay=true)
sma1 = sma(close, 8)
sma2 = sma(close, 13)
plot(sma1, color=color.green)
plot(sma2, color=color.red)
cross_bull = crossover(sma1, sma2)

plotshape(cross_bull, style=shape.triangleup, location=location.bottom, color=color.green)

low0 = low[0] < low[1] and low[0] < low[2] and low[0] < low[3]
low1 = low[1] < low[0] and low[1] < low[2] and low[1] < low[3]
low2 = low[2] < low[0] and low[2] < low[1] and low[2] < low[3]
low3 = low[3] < low[0] and low[3] < low[1] and low[3] < low[2]

lowestx = low0 ? 0 : low1 ? 1 : low2 ? 2 : low3 ? 3 : 0
delay = 0
delay := cross_bull ? lowestx : 0

bgcolor(cross_bull ? color.yellow : na, offset=-lowestx)