measuring ahead

Brittany
I'm due with a little boy July 21st. This is my 4th. I'm measuring 4 week ahead. Has anyone measured this far ahead and not gone early? My 3 other kiddos were all under 7lbs and were all right on time and I was tiny with them. Any advice or input would be fantastic! I'm just trying to figure out if I should prepare to have baby sooner than they say.