I see what you mean! Very small combs and I suppose some could be roos. Hard for me to tell from this pic but usually at 18 weeks, if they have small combs, they are more than likely pullets. But if you're really curious, post pics in the "Breeds/Sex" section. If you include this pic plus body shots that show tail/saddle feathers and sometimes even leg shots help, there are people that patrol that forum and can help you determine if they are pullets or cockerals. But, if you brought sexed pullets, that's probably what they are. Time will tell in any case.
If most of your pullets have combs of this size, it could mean they are not that close to being mature enough to lay. You might be waiting for several more weeks before you start getting eggs. Or, maybe you'll get a few that start laying and the others take longer. The range of when they lay is very wide, like from 17 weeks to even up to 12 months. And, we're going into winter which means the number of hours of daylight will become less. This triggers lower egg production and it's possible that pullets that have not started to lay yet will wait and not lay their first egg until spring. It's all pretty variable and each chicken is an individual with their own uniqueness. Each will probably behave slightly differently, some laying soon, some later this year, some not until next year.
We can be patient and remember to enjoy the journey and the learning process! Have fun and good luck to you!
Guppy
If most of your pullets have combs of this size, it could mean they are not that close to being mature enough to lay. You might be waiting for several more weeks before you start getting eggs. Or, maybe you'll get a few that start laying and the others take longer. The range of when they lay is very wide, like from 17 weeks to even up to 12 months. And, we're going into winter which means the number of hours of daylight will become less. This triggers lower egg production and it's possible that pullets that have not started to lay yet will wait and not lay their first egg until spring. It's all pretty variable and each chicken is an individual with their own uniqueness. Each will probably behave slightly differently, some laying soon, some later this year, some not until next year.
We can be patient and remember to enjoy the journey and the learning process! Have fun and good luck to you!
Guppy