Actually, the muzzle smoke would appear before the recoil kicks in.       Analyzing recoil with a pistol with a high speed camera - YouTube              In this video, you can clearly see a shot fired in slow motion, showing recoil kick in well after the smoke trail. You'll find this holds true in other slow motion firing examples with other types of guns, such as rifles. The smoke generally dissipates almost entirely before recoil kicks in.     And, if you look at the smoke trail coming out of Obama's gun, it lines up with the angle of the barrel, otherwise there would be more smoke below the level of the barrel along the pink line. So one would have to conclude that recoil hadn't kicked in yet in this photo and the lines are accurate.