Planning pregnancy around deployment.. is it possible?

My partner deploys every 18 months for 6 months at a time. I want him to be here for the birth and first so many months so he can take leave and experience the newborn stages with me like he did our most recent child. Is it crazy to try and get pregnant before he deploys and just be ready to pop when he returns home?? I'm going crazy trying to figure out how to do this. Anyone else been through this before?