When Parenthood returns on Thursday at 9 p.m. (NBC/Ch. 5), the narrative jumps forward several months. It's a big enough jump so that Jasmine (Joy Bryant) goes into labor and gives birth. And, for the first time, Crosby (Dax Shepard) finds himself caring for an infant. And things don't go well.Which, Shepard insists, requires some acting on his part."It's the opposite of what you might imagine because now I love babies," he said.Shepard and his fiancee, Kristen Bell, became first-time parents in March when their daughter, Lincoln Bell, was born.Dax and Jasmine's baby is very difficult. Dax is struggling. And he's worried that he's not bonding with her."I'm supposed to be frustrated with the crying baby in the scene," Shepard said. "And I'm. like, 'Oh, my God - look at this little stinker! My little girl was just like this a month ago.'"His newfound fathering abilities do come in handy on the "Parenthood" set."It definitely helps me because I don't have kids," Bryant said. "So he's telling me how to hold the baby."Right. I got secret weapons," Shepard interjected, quoting "the five S's" from the book "The Happiest Baby on the Block" - "swaddling, sideways, swaying, shooshing, and sucking. And I will put this little baby through its paces."Makes that babies, not baby. As is the case with most TV shows, an array of infants are used on camera."We have about 65 twins, I think, where they all work for 30 seconds," Shepard said. "And we've got to shoot for 12 hours with them, so it's just a conveyor belt of babies. 'Action. Cut. Action. Cut.' We're employing 90 percent of the newborns in L.A."And he's a lot happier about it than he would have been before he became a father."What's funny is last year, whenever we would be stuck in a scene with [Kristina] and Adam's kid it was torture," Shepard said. "But now that I have one, I love being around the baby. Yeah. I got, like, a software upgrade. Now I love it."