Oohh ok, so this is something I actually know how to answer thoroughly since the lab I worked in in undergrad worked specifically with swordtails! So!
With pure bred (no hybridization) Xiphophorus variatus, malinche, birchmanni, and cortezi, the fry usually had some early developing males by three months. This was with twice daily feedings of BBS (microworms if no BBS available), and a tank temperature of 76 F.
That being said, evolution kinda decided to pull a skid turn. Swordtails (and also other poeciliids) have these things called early developing males and late developing males. Some males will develop their sex organs very, very quickly (90 days at earliest), at the cost of having stunted growth. Other males will develop their sex organs much more slowly, and therefore be much larger in size and more colorful. With female swords, we tried to separate their brothers out by three months, and did continuous tests. However, at around 3 months, it was usually pretty visible which fish were producing gonopodia, and which fish had more of a fan shaped ventral fin.
If I remember, orange sunsets are some variation of X. helleri crossed with X. variatus, and maybe some X. montezumae in there as well. Never managed to grow my fry out to adulthood, but the males in the lab I worked with, usually grew tiny stubby swords by 4 months of age. The lab fed a staple algae flake if we didn't have the time, but most days I was feeding repashy soilent green, and for the fry that had graduated from BBS, a little bit of Repashy spawn and grow.
So many fish/plants/inverts to keep, not enough aquaria.