I had a quick one done at 18w6d during my anatomy scan. The baby did look a bit scary as they don't have much fat at that point. (or maybe my baby is just scary looking!)
The sonographer said that 28 weeks is the best time to have it done as they are chubby then and still have lots of room in there. To be honest I wouldnt get one done again that early but if you don't have a choice then go for it! It's still great to see your baby on 4D just don't be alarmed by their looks!
Ok i'm ready to see my scary baby.. I was also hoping to use it as a double check on the sex of bub too

Also so it's only $100 but if it was $300 or more i might not get it done IYKWIM