By polished I mean the ending pops back to the beginning with a jerk.

All right. Then what you want is a loopable animation. Poser can do this for you automatically, though it might require some tweaking, depending upon where everything ended up at your final keyframe.

Add a few frames (perhaps five or six) at the end of your animation. Then enable loop interpolation.

Animation menu --> Loop Interpolation

Poser will use those extra frames to move everything back to its starting point.