'19 Kids and Counting': How Jill and Derick Dillard Are Prepping for Their Baby Boy

— -- It's four months away from the expected arrival of "Baby Dilly" in March.

But "19 Kids and Counting" stars Derick, 25, and Jill Dillard, 23, are already getting ready to be the best parents they can be.

"I am learning a lot about birth," Derick told People magazine earlier this week. "We are doing our homework together, and I keep reading new things, the medical aspects are fascinating to me."

Jill added about the birth plan, "We are really on the same page. The more Derick learns about birth, the more he feels that natural childbirth makes sense. ... Derick's great at helping me with relaxation, and really good and supportive."

The couple also keep a journal to one day share with their son.

Also, Jill -- who's doing prenatal workouts -- said, "After the holidays, we'll get started on the nursery."