They were born on 10/23/15! So this month they are cresting on laying age. They seem to be slow maturing, though, since they're oddly enough still filling out. But ain't that just how it goes... won't be 'til they've been laying and mating for awhile that I stop seeing differences in them every week, haha.
I actually don't use a prefab crow collar, just an inch wide strip of velcro! I would like to try the ones sold by mypetchicken, but at over $20 a collar, that's not exactly economical (and have you seen the cost of the bowties?? Highway robbery!)
The trick of it for me is finding a fit that restricts their volume but also allows them to swallow pellets without trouble. They have no trouble eating crumble, greens, fermented feeds/mash or drinking with just about any fit, but these big bulky pellets I primarily feed have made finding a good fit an issue. My feed store special orders my pellets for me, so I'm stuck feeding them for several more weeks until I can switch to crumble. It takes a couple days of listening and checking to get it right. Luckily with naked necks it is easy to spot when there's not enough room and you can readily find the tube to the crop, so even during fitting it is easy to know you're not pressing/crushing it. Also if something does get stuck, they don't choke. Thank you glottis! So luckily finding a good fit has not been dangerous. If your boys have bow-ties, I find putting it right under the bow-tie helps most. Lower and the fit gets loose, higher and it doesn't do what it should.