Did you do the thigh instead of the back of the neck? I heard somewhere on here of someone having paralysis in their silkie after trying the neck site, so I think I'll try for thigh. I just hope there's enough skin to get a subcutaneous rather than getting the muscle.
New chick - As far as I know (from watching a Dirty Jobs episode snippet on YouTube) the hatcheries use an automated needle system - they hold the back of the chick's neck up against the machine and it's pressure-activated and delivers the shot. I bet it's not the most accurate delivery - hence my decision to just do the silkies and standard fowl together myself. I think it's about $30 or so and gives you way more vaccine than you need. Oh well. Could be worse.
If I do it, I'll certainly do it on day 1 or 2 after their delivery and they won't be getting outside exposure until they're a few weeks old.
I know small flocks can be replaced, but I certainly don't want to lose ours. It was trouble enough trying to get a date when all of the desired chicks are available - and if we replace we'll need the minimum for shipping all over again. Just because my husband wants the sexed silkies! I should really make HIM do the injections. He'd pee his pants.