We had one for DD1 at about 34 weeks. It was very nice and all that and we got some nice pics and a video. I would never ever go before the 20 week scan for two reasons; one, I wouldn't trust being told the sex, and something like what happened to Aimz would be extremely upsetting for me. Two, they have no fat earlier on and don't look cute IMO. The scan at 34 weeks looked exactly like DD1, very cool. We didn't have it done for DD2 because it's really a first time baby thing for me. We didn't feel it was necessary and couldn't justify the cost a second time.