updated 11/18/2009 AT 10:00 AM ET
•originally published 11/18/2009 AT 12:40 PM ET
“I just spent the last weekend – Mom was rehearsing for Chicago – being Dad without a nanny, without Mom, and didn t burn the house down,” the Fall Out Boy bassist, 30, told PEOPLE on Tuesday at the American Eagle Outfitters Times Square store opening. “So I m pretty excited about that.”
The couple’s son, Bronx Mowgli, turns 1 on Friday, and will get to enjoy the company of both parents and friends at a SpongeBob SquarePants-themed birthday party in Los Angeles.
“He likes Bob and he likes guitar – which he calls ‘itar, so we’re going to have a Spongebob party for him,” Wentz said.
On the guest list? “A bunch of friends,” he said. “Like all the guys in Blink  and a couple friends that have kids [are coming over].”
Simpson-Wentz, 25, makes her Broadway debut as Roxie Hart Nov. 30. (She played the role in the London production in 2006.)
Bronx may need a babysitter that night. Asked if he will be attending his wife’s debut, Wentz said, “I think I will be.”