When is the right time to become pregnant?

Just asking cause going to be 18 year of age on July 1st and I'll be graduate early which tht will be next year. Them heading off to tech for 2 years and then going to a four year college to finish tht and I'll be done with a tht to leave my life now....I mean I want to wait it doesn't bother me waiting but I don't know wen the right time to become pregnant. I don't want to do it now cause its going to mess up my life here.. Me and my bf want a baby but I told him to wait but don't know how long will be tht to wait. Its hard to think tht. I had this on my mind haven't told him yet tht how long he want to wait...