why the 2nd raikage? they have never been seen in combat. i assume you mean 3rd and 4th, not 2nd and 3rd.
either way, it takes, based on calculations i made in my head and with no mathmatical basis, aproximately D*.00000000003 seconds, where D is the distance, in centimeters, between sakura and the 4rd raikage.
(4rd raikage is fastest, therefore faster than haku, who is lightspeed. lightspeed is 300,000 Km/H, so sakura will last the amount of time it takes for the 4th raikage to reach her.)
the other 4 kages are attacking her, but they aren't neccicerily as fast, so they will reach the pink mist after the 4th raikage.