Vanessa Minnillo: I made 'two rookie mistakes' changing son Camden's first dirty diaper

Motherhood isn't for the faint of heart. Just ask Vanessa Lachey.

"I haven't slept since September 12," the Wipeout host, 32, tells Us Weekly of her round-the-look care for 8-week-old son Camden. "It takes so long to feed and change and swaddle him. But it's worth!"

Lachey -- wed to singer Nick, 39 -- is sharing her new tricks as spokeswoman of P&G's Have You Tried This Yet? campaign. The Charleston, South Carolina, native opens up to Us.

PHOTOS: Vanessa and Nick's son Camden's baby album!

What's been your toughest challenge?

I think the diaper thing. His first blowout, I made two rookie mistakes: No. 1, I didn't put a diaper underneath the old one, and No. 2, I didn't let him finish. Nick and I laughed ourselves to tears.

How is Nick handling diaper duty?

He's the best! I'm really lucky. He changes them a lot. Since I nurse, Nick sees that as his bonding time. He'll talk and sing to him while doing it.

PHOTOS: Sexy celeb dads

So sweet! What are Camden's milestones?

He's smiling at the sound of our voices now. He's so peaceful -- he just sits there and takes it all in with his bright blue eyes. He has his daddy's eyes!

PHOTOS: Vanessa and Nick's most romantic moments

Advice for new moms?

Don't be scares to accept help. If someone wants to come over and cook or clean, take it!

ALSO ON WONDERWALL:

Nick and Vanessa Lachey introduce baby Camden

Where are they now: boy bands

Nick Lachey improves his foot massage skills