Maci Bookout's Instagram

Maci Bookout -- And Her Baby Bump -- Gets A Super-Sweet Kiss From Son Bentley

Looks like Benny and his sister Jayde are already besties!

Maci Bookout's cutie pie son Bentley is gearing up to be an older sibling to his baby sis on the way, and the "Teen Mom OG" cast member shared a darling glimpse of the six-year-old already showering his mama's mini-me with some love. Prepare to outfit Benny in a "best big brother" T-shirt as soon as this petite princess makes her triumphant arrival.

Maci -- who will welcome Baby Jayde Carter in June with beau Taylor McKinney -- added the heartwarming Instagram snapshot below of her son and longtime boyfriend giving her burgeoning, purple-clad bump a couple of kisses. Better watch out, puppy Bonnie -- everyone wants to cuddle up to M's tummy!

"Jayde and I are the luckiest girls in the world thanks to these two wonderful men!" the 23-year-old wrote along with the aww-worthy image from a recent maternity photo shoot which features M's doting guys holding -- and sweetly smooching -- her eight-month belly. Only a short matter of time until they're actually cradling the precious peanut and B is besties with his younger relative.

The Tennessean also posted a loving pic with T, and there's no denying this couple is really ready to meet their little one. It's the final countdown...

Be sure to catch M on the season finale of "TMOG" on Monday at 10/9c -- and for a fun rewind, watch B learn that his "mother is having another" in the clip below!