Im projected to start my period 12/9

Danielle • I'm 28 years old with 2 boys! A 4 year old who will be 5 in October and a little boy that turned 1 august 9! My husband and I found out september 14 that we are expecting our 3rd baby! Praying for a happy healthy pregnancy to everyone!!
Are there any ladies that are supposed to start on or around12/9 and what day do you plan on testing?