when would you say is the best time for a 3D/4D ultrasound

Lindsay • Wife & Mom | 💓
Currently 21 wks pregnant and we're wanting to get one done around 32 ish weeks. Wondering if that will be a good time? 
My cousin just went at 36 weeks and they couldn't see much because they baby is too big? 
But I don't want to go too soon. 
Pics of your 3D's with how far along you were would help!