Question for the experienced Mommas

At my 8 week scan baby measured 2 days ahead. At my 12 week scan baby measure 6 days ahead. At my 20 week scan baby measured 7 days ahead. The doctor said they only change your due date if your +/- 7 days at those early scans. Any mommas with previous experience of babies measuring ahead. Have they come early, on time or late and by how many days.