I had this question a year ago when deciding to add a Silkie to my mixed flock. I already had New Hampshire Reds, Speckled Sussex, Easter Eggers and Buff Orpingtons.
I wish I had followed the advice of some of the others on BYC. I read several posts about not mixing Silkies with other breeds because of their docile and subservient nature and their tiny size.
I ended up adding a beautiful little Silkie to my mixed flock and very quickly started to notice that she was being picked on. Especially by the NHR. The only chickens I had that seemed to leave her alone were the Easter Eggers. All the others, including the Buffs could be downright mean. I finally had to give her back to the nice lady I purchased her from after one of the NHR's took a chunk out of her neck.
Silkies are the best. They are sweet, don't mind being held and their little tinted eggs are just perfect. My little silkie layed 3 to 4 eggs a week once she hit 9months old. I actually got 2 at first but by 6months I started to notice one getting less of a 'poof' and more of a red comb. He ended up being so gorgeous the lady I got him from was happy to take him back.
I def think its easier to get all the same age. Instead of a hatchery you might want to see if there are any hobbiest silkie breeders near you because you would be more likely to get older birds that you can be sure that they will be female. As I said earlier mine did not show signs of being a rooster until 6 months of age versus other chickens that you can start to tell at 4 to 6 weeks.
Silkies are wonderful. When I have a larger property I plan to have a separate pen and run just for a few silkies. They are just so cute and sweet and I think they lay fine for such a tiny thing.
Good Luck!
