3D/4D

We are having our 3D/4D ultrasound at 27w3d, my boyfriend works away from home so this is the only date we can get before I’m 31w along. It’s been 7 years since my last one so I don’t remember much but am just making sure this is a good time? The ultrasound technician recommended around 28 weeks. Close enough huh? Just want reassurance that it’s not too early.