The couple is eagerly awaiting the birth of their second child and Schreiber said on Friday the bub is set to appear any day.
"Soon," Schreiber told AAP.
"Our first baby came early and I suspect this one will as well."
However the San Francisco-born actor and Tony Award winner is hoping baby delays its arrival for a couple of days.
Schreiber was in Los Angeles on Friday to promote his new film Defiance with co-star and new James Bond, Daniel Craig, while Watts was resting in New York where they plan to have the baby.
With his mobile phone in his pocket, Schreiber was ready to jump on a plane for the five-hour LA to New York flight if Watts called.
Defiance, set in Belarus in 1941, tells the true life story of a group of Jews who escaped the invading Nazis by hiding out in a forest for three years, establishing a new community and launching sneak attacks on the Germans.
The film, directed by Oscar winner Ed Zwick, is gathering huge Oscar buzz, with the National Board of Review in the US just naming it one of the top 10 films of the year.
Baz Luhrmann's Australia failed to get a mention.
Schreiber and Watts welcomed their son, Alexander, into the world 16 months ago and 41-year-old Schreiber says they are prepared for two youngsters under the age of two in their Manhattan home.
"Life gets a lot busier," he said.
"It also gets a lot more enjoyable in many aspects.
"There's a sort of every day terror you are exposed to that I'm still not accustomed to.
"You can be pouring yourself a cup of coffee and you turn around and realise your 16-month toddler has the ability to climb two chairs and get on to a dining room table and stand on one foot as he reaches for a lamp.
"It is just remarkable to me he could do that."
Defiance opens in Australian theatres February 26.
