It is kind of true. Some hatcheries breed a special breed of chicks. When they are hatched the males and females have different length wing feathers. These flocks require special care to keep the genetics of those wing feathers pure. The feather sexing gets done to day old chicks, not 2 month old chicks.
However, at 2 months old you should start to notice the special feathers your cockerels will have. The males will start to grow the pointed saddle feathers that are a sign of it growing up to be a rooster. The combs on the cockerels will start to turn red at about this age while the pullets' combs will stay light colored. There is no length of wing feathers test at this age to determine sex.
If you take some good pictures of your birds there are people in the forums who are very good at determining sex when chicks are 2 months old. You would need a good picture of the head including the comb. You would also need a side picture with the bird standing naturally. These need to be close up pictures.
Feather sexing only applies to specific hybrids that are bred for feather sexing. Pure bred chickens are not feather sexable. You will have to wait until they're 8 weeks old or so to sex these guys. Beautiful clutch of babies though!