B.F.
Hello, I'm B. and I have two children ages 5 and 3. I always went by the day they were born. Like my daughter who is 5, her birthday is April 10th. SO lets say May 10 is one month old, and so on. Anyone I have talked to usually goes by the day, not by the weeks. However you can say he is so many weeks old. Like if he was born on the 1st day of the month and its the 14th day of the next month, then he would be 6 weeks old. 4 weeks for the month and an extra 2 weeks into the next month. I hope that helps. B.