It is begun from the left of the previous stitch. The modification in the beginning point produces a twist in the leg of the stitches.
Understanding the Chain Stitch is a should find out the Twisted Chain Stitch. It looks gorgeous in embroidering the edges of any style.
1. Pull out the threaded needle through A
2. Partially insert the needle through a point, positioned left to the point A
3. Pull out the needle through B
4. Without pulling out the needle entirely, pass the thread from left to right
5. Continue the process.
The Image Guide: