Congratulations to Jimmy Fallon and his wife, Nancy Juvonen Fallon, who became first-time parents yesterday. A spokeswoman for Fallon confirmed the 38-year-old “Late Night” host and his wife welcomed a baby girl yesterday at 6:21 a.m. while the whole world was on royal baby watch, waiting for William and Catherine, the Duke and Duchess of Cambridge, to emerge from the London hospital with their newborn son. Fallon’s rep Claire Mercuri