Nice pic.If I remember correctly mine start showing around 12 weeks. very clear difference by 16 weeks as pictured. Pretty sure we get some "crowing" by 12 weeks as well, at least strange, disturbing screaming... that eventually sounds like crowing
These are 16 weeks with clear saddle feathers and you can see the difference in comb and waddles, our pullets have smaller combs than some strains of Lavender Orpington though.
Mine all started crowing long after I knew they were male. The male blk orp from my post #1856 was my youngest at about 12 weeks. He was an early bloomer in EVERYTHING. We had no adult rooster for a couple months, so that male started mating the mature hens shortly after crowing. Before he was 16 weeks old, we had fertile eggs. (I know because I saw the bulls-eyes, and did a test hatch at that time.)
Most of my other roos waited until 5 months before they started crowing & mating. Of course my orps take at least a year to get to size & the hens usually don't lay until they're 8 months old. That's one of the drawback of having 9-14 lb orps.