Good looking group you got there. Just be patient, they'll settle in but sometimes it can take a long time. Especially if you keep changing your routine....lights on, lights off...just pick one and stick with it. At 18 months they're actually still kinda young, yeah they should be sexually mature now but wouldn't call them "full adult" just yet. Like
tlindsey
said spend as much time as you can with them and a year from now you'll have the pack of killer p's you're looking for. Good luck bro.
BH

BH