It could take awhile for the full change...
I purchased two female pylei fairy wrasses. One started changing then went back to completely female after getting internal parasites. This made it weak to the point the other nipped some good chunks of fin off. The other female started to become alpha. This happened back in March-April, and she still is only showing some signs of going male. These signs include slowly growing pelvic fins, blue color coming in, and overall growth in all fins. Nothing too major yet. I may very well have a male already had the one female not gotten internal parasites (after two weeks of Prazi too).
Good luck, and enjoy the transformation!