Pregnant Jill Duggar and husband Derick Dillard shared a photo of her baby bump at 40 weeks ahead of their engagement anniversary weekend — see the Instagram snapshots!

I wonder if #babydilly will decide to come on the one year anniversary of my engagement to @jillmdillard this weekend.

A photo posted by Derick Dillard (@derickdillard) on Mar 27, 2015 at 4:50am PDT

Will baby Dilly be here to celebrate? Jill Duggar and Derick Dillard are gearing up to celebrate their engagement anniversary this weekend — but their son still hasn't arrived! The parents-to-be shared what could very well be Duggar's last baby bump photo on Friday, Mar. 27.

"I wonder if #babydilly will decide to come on the one year anniversary of my engagement to @jillmdillard this weekend," Dillard, 26, captioned an Instagram photo. In the snapshot, Duggar — like so many times before — holds up a small chalkboard to document her progress. "40 weeks 2 days," it reads.

Dillard popped the question to 23-year-old Duggar this time last year, and they tied the knot in June 2014. Keeping track of their special milestones, the lovebirds also took note of their nine-month wedding anniversary last week.

"Happy 9 monthiversary @jillmdillard !!! A LOT has happened since June 21!" Dillard captioned an Instagram collage on Mar. 21, as he showed off his #newdad T-shirt and mug. "I am blessed beyond measure and every day is even better with you baby! You're my best friend, and I love you with all my heart! #newlyweds #newdad."

Papa dilly installed the car seat today! Ready for #babydilly to come any day! #duedate @derickdillard

A photo posted by Jill Dillard (@jillmdillard) on Mar 24, 2015 at 5:06pm PDT

The 19 Kids and Counting couple sure are waiting patiently for their baby boy. On Mar. 24, Duggar posted a photo of her hubby gearing up for the big day. "Papa dilly installed the car seat today!" she wrote. "Ready for #babydilly to come any day! #duedate @derickdillard."