When should I be transplanting?

I too would say now, maybe another 4-5 days at most, the roots will be at the bottom already and looking for more room. For an idea as to the size of the roots on a young seedling, go to my diary "cannabis conundrums" and in week 7 there are pictures of the exposed root system of a 3 week old seedling and this may give you an idea as to what is happening with your seedling. Remember to water in well after transplanting. If you are really keen, giving your seedling a dose of seaweed extract/tonic a day before transplanting will boost its strength to cope with being transplanted. Hope this helps,......... Organoman.

I would wait another 3-5 days. Also transplant when the medium is dry not wet.

I would do it now. Put it in her final container as well.

You can do it now if you are very careful, or when she is a bit bigger and stronger. good luck mate 💪