Advice for Extending Chastity Device Wear Time

My record for wearing a chastity device is seven days, and I used the CB6000. Any advice on how to last longer in one? I’m using an all-metal setup with a metal ring, but the cage part is open. The balls feel pretty snug right now, which makes it tricky to get into them. It’s like once they’ve been out for a bit, putting them back in becomes difficult.