Growth Scan Curiosity

We are finally having baby #2 after 7 years of trying and my first baby was big because of gestational diabetes (10lbs 5oz), this time I have controlled the diabetes better and gained a lot less weight but doc is still expecting me to have a 10lb baby. Because I had my daughter so long ago I cant remember how accurate our growth scans were the weeks leading up to birth. My last scan with this baby they said he is measuring 9lbs already and I am only 36weeks (c-section is scheduled in 2 weeks).