I think I can se some free space between the band and the leg in one photo. as long as it will freely slide up and down it's OK. But their legs do continue to thicken so you need to be careful. With any kind of eg band you need to regularly check them.
There can be lots of different reasons you want to mark them. That could be record keeping or to tell them apart. If I remember right ID might be required at some shows if you show them.
There are lots of different ways you can mark them like wing bands or numbered leg bands. I use colored zip ties, the color on the left leg tells me which year they were hatched and the colors on the right leg are individual ID for identification and record keeping. Some people use toe punching, essentially using a small hole punch to punch a hole in the membrane between toes. That could be useful to mark young chicks. You can use food dye to mark chicks but you have to keep renewing it. With some methods you can see at a glance which is which, others you may need to catch the chicken.
You need to work up the method that works for you.
There can be lots of different reasons you want to mark them. That could be record keeping or to tell them apart. If I remember right ID might be required at some shows if you show them.
There are lots of different ways you can mark them like wing bands or numbered leg bands. I use colored zip ties, the color on the left leg tells me which year they were hatched and the colors on the right leg are individual ID for identification and record keeping. Some people use toe punching, essentially using a small hole punch to punch a hole in the membrane between toes. That could be useful to mark young chicks. You can use food dye to mark chicks but you have to keep renewing it. With some methods you can see at a glance which is which, others you may need to catch the chicken.
You need to work up the method that works for you.