At 50 inches, doubtful it's a clonelet or seedling, lol. :thumbsup: But how small a pot are they in now, and how large are you looking to go?

If she has just started showing sex, it's time to flower. Especially if headroom will be an issue, as a 50 inch plant will still stretch. (Indoors, right?)
If indoors, I hope it's a heavy indica that doesn't stretch much, or you may have a problem with overall height. Plant height, plus heat buffer between plant and light, plus the size of your reflector...is there room for more vertical growth?
What kind of lights are you using?

If a transplant is necessary, it's necessary. Use extreme care when transplanting. Might want to think about gently tying-up the branches with some string. Kinda like how they ship Christmas trees, with the branches all bound-up. Helps prevent bent and broken branches with larger transplants.
Use care with the rootball, as any damage will delay harvest time while she repairs herself, and heavy damage can stress her into hermaphrodism.