By Alison Schwartz
February 19, 2011 02:30 PM
Denise Truscello/WireImage

Before they were Eddy and Nelson, Céline Dion had a special way of referring to her newborn twin boys: Baby A and Baby B.

The singer, 42, says she didn’t name her sons, now 4 months old, at the hospital, instead waiting about a week – to husband René Angélil’s frustration.

“René said, ‘Listen, people are starting to call me. What’s their names?’ ” Dion tells Oprah Winfrey in an interview scheduled to air on Monday’s The Oprah Winfrey Show. “‘I can’t tell them A and B again – that’s not working.’ ”

Besides, Dion, who’s also mom to René-Charles, 10, says the nicknames were too confusing – she even contemplated using different initials at one point.

“It’s like, ‘Was the hat switched? I thought this was Baby A,’ ” she says. “And I’m like, ‘Stop [with] the As and the Bs. I’m going to do C [and] Ds right now. My name is Céline Dion with a C and a D, so don’t push me because I’m close to the edge!’ ”

Now that her little guys are named and settled into her Jupiter Island, Fla., mansion, Dion is gearing up for her next venture: She’s making her way back to Las Vegas beginning March 15 with a new show at the Colosseum at Caesars, where she ended a five-year run of sold-out concerts in 2007.

“The love and what I feel inside, what we have accomplished – I don’t know how to put it into words,” she told PEOPLE in December of life with her twins. “It’s bigger than life itself.”