Moving on the circumference of a circle in the closest direction

I am the center of the circle. The radius is 0.5. I have 2 markers, marker A is spawned 0.5 blocks in the direction I am looking at, and marker B is spawned 0.5 blocks in a different direction (the origin is still me). I want to make marker A move along the circumference of the circle in the direction that will make it reach marker B the quickest. Any suggestions would be appreciated