Kailyn Lowry's "littlest baby" isn't so miniature anymore: The Teen Mom 2 tot is about to be one!

But before Baby Lo Lux officially enters single digits (on August 5!), we're remembering his MTV debut that came courtesy of a season finale installment last November. Little rewind: The "mother of boys" opted not to film the birth (can you blame her?), and the then-unnamed newborn was first seen when Lincoln got to meet his little brother for the first time.

"Is my baby brother out? Where is it?" Kail's middle son asked in the clip above, while running toward his mom and the newborn.

Following some hugs and initial interactions, Kail tried to get her boy's take on a moniker. However, Linc's suggested name of "Climber" was immediately out of the running.

"You feel so big to me, now that he's here," Kail told Lincoln as he cuddled up to her. Later, Isaac joined in on the fun -- and they both happily kissed their little brother.

Relive the special scene in the video above, and offer your early well wishes to Lux in the comments. And don't miss Kail on the Teen Mom 2 this Monday at 9/8c.