The flop must be dinged (IMO) to produce a true flop that results in minimal roll after landing . Yes, hit the 'dang line' (to left of ding line) if you don't want to change aim, but it wont be a true flop
How far left to aim is the question, My answer (adjust as required for wind and slope in landing zone) is: 20 yd flop, aim 6 ft, (3 squares on putting grid) left; 30 yd, 4 squares left; 40 yds, make it 5 squares left.
Prev responses have been right on for impact of wind.