Per the New York Times, NYU President Sexton saw an egg Tuesday when Bobby and Rosie were off the nest briefly.
And so the new season begins! Red-tailed hawk eggs are typically laid every other day (with three eggs in total being the norm).
The first time regular hawk-watchers saw Bobby and Rosie copulate was on February 15th. Of course, it's possible they mated before then. This first egg seems to have been laid on March 6th. That means it took roughly 20 days between mating and egg-laying.
Per Wikipedia, it takes between 28-35 days for eggs to incubate then hatch. That would mean the eggs could hatch sometime between April 3rd - 10th.
The web cam is supposed to be up and running early next week.