Thank you for this! I have one BO who is 4.5 weeks and I'm trying to watch for signs but as she's the only one it's difficult without having another to compare her to.NOTE: i am NOT asking for help here. This post is to help others!
If you’re trying to sex your Buff Orpingtons right now, take a look at this picture!
This is my BO cockerel and pullet, both are 6 weeks old.
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Although I also have two SS and I can't see much difference between them, only one is feathering slightly faster, comb and wattles are the same so that's not helping me much

Can I ask when you saw the change start? One of my Marsbars was an overnight Roo, one day tiny comb no wattles the next day bright red huge comb and wattles starting

I'm interested to know if it was a slow growing change or if his popped up overnight and at what age you noticed an obvious difference.
Sorry for all the questions!