Are your roosts actually suitable for chickens?
They need to be at least an inch wide, more for some breeds, preferably flat not round, at least a foot off the floor, higher than the top of any nest boxes and with in an easy jump for the chickens.
If they are good then at bedtime sprinkle some...
My silkies are 24 weeks old and I saw them trying to mate today so hopefully I'll be getting eggs soon. My RIR and others are only 20 weeks so they might be getting ready in a month or so I hope.