The wing feather technique doesn't work for certain breeds, including silkies. Apart from paying for a DNA test, silkies are one of those breeds that are impossible to sex until they are around 3 months old (regardless of color).
At 3 months, you can expect to see larger combs/waddles on any cockerels. Their crests should have 'streamer' feathers coming out from the backs of them. 'Streamer' feathers are just feathers that are longer than the rest of the crest feathers, and tend to fan out a little. Pullets will have almost non-existent combs/waddles, and no streamer feathers. Their crests will be rounder. If you're unsure, we should be able to help you, given clear photos of crests, combs, and sides.
Name wise, I would just give them some gender neutral names or a name that can easily be changed to fit a different sex. Good luck!