Newbie

I would say that is just going to take time. Switching other tasks to that arm might help speed up the coordination.

I used to throw with both hands. I was a solid A player right-handed and a good B+ left-handed. Then I met a woman. She hated playing with me when I played left-handed. I gave it up for a few years and never practiced left again. I had the habit of doing everything with both hands when I was fighting. Well, I gave up the girlfriend, gave up fighting, and I guess I gave up throwing with my left hand. I suppose practice is everything. Take what you have learned from throwing right-handed and apply it to the left. However, with that said, my left-handed stroke was different than my right-handed stroke. I threw harder with the right and tended to float my darts to the target with my left. Practice, find what works, and do that. 

@darthelp