how to get a clear ultrasound? // 16w3d

Hey girls, so I'm finding out our baby's gender today and I was wondering just about how much water I should be having today in order for baby to be more visible in the ultrasound?
I have a 40oz bottle.
And also, they would prefer if baby is active so, how long before the ultrasound should I drink some orange juice in order to get baby moving today?
Ultrasound is 8:30pm tonight. (yes, they work pretty late, which is awesome because my husband works and gets out around 6:30 today)
Would truly appreciate all the advice and opinions I could get! 
❤️