Good luck with the hatch!
Unfortunately no you can't sex them at that age. There is vent sexing but I'm not going to advise on that. Pretty much if you know how to do it correctly and you are experienced then it's usually accurate, if you've no experience with it, it can be dangerous and inaccurate.
If you are hatching UK type silkies, you usually have a pretty good idea on sex at around 11 weeks old.
If you are hatching USA type silkies, expect to wait anywhere from 4-6 months before you know what's what!
Partridge silkies of all the colours can usually be sexed sooner.
Silkies are lovely just a pain to sex