Before the new season of his show premieres Tuesday night (10 p.m. ET on TLC), Klein shared with PEOPLE some of the lessons he's learned so far:
1. Dads Can Do Diapers
"I hated changing diapers at first until I got good at it," says Klein, who jokes that at first his job was to "hold Will's legs and gag." But now that his confidence has grown, and he explains: "It took Jennifer not being around to do it to teach me I could do this. I don't know if I could fly a plane if the pilot wasn't around, but I can change Will's diaper on my own."
2. Safety Gates Are Great
"When Will was in foster care, he was in a crib and he rolled everywhere," Klein says. "Now that he has his own bed, we learned quickly that a safety gate on his bed keeps him in so he won't roll out."
3. Lunch with a Side of Heimlich?
When Klein took Will out for his first "guys-only" lunch, he says that he expected that the grilled cheese sandwich he'd selected for his son to be very kid-friendly. Until it turned out the cheese was too stringy.
"I cut it up in quarters, but it must have been too rubbery because he started choking," says Klein. "My fingers were in his mouth before I knew it, getting the piece out. Mom would have done it better, without so much flavor of fingernail I'm sure, but he was OK. We were OK."
4. Grandparent Nicknames Can Be Tricky
"All the grandparents are settling in on their names and some haven't gotten back to me," says Klein. "Jen's dad is pushing El Guapo (Spanish for 'The Handsome One') but I'm not sure that's going to fly."
So far, other names that are being considered are: Pop Pop for Klein's dad, Grammy and Grandma.
5. Make 'Em Laugh
Klein says that while Will loves meal times and play time, nap time can be a challenge. Humor helps.
"Even if Will's miserable, you can make him laugh and then he'll forget why he was sad," Klein says. "Getting him into the bed is the trick, but once he's in there, I'll make him laugh with a face or a tickle and he's happy again."
For exclusive photos of the family and much more on the adoption, pick up this week's PEOPLE magazine, on newsstands Friday