Private scan

Hi I live in the UK and tomorrow I’m going for a private scan so we can take my 5 year old son along and show him his new brother or sister. I’ll be 12 weeks 5 days. I have my gender scan booked for 16 weeks but I’m thinking about masking the guy doing the scanning if he can predict the gender. Obviously It wouldn’t be confirmed until 16 weeks but do you think he may have a good idea?