If President Obama had delayed the announcement of Osama bin Laden's death, it might have given the CIA more time to trawl through the data seized in the raid and track down other al-Qaeda leaders. So why announce it right away?
Following the operation, officials across U.S. government agencies told their Pakistani counterparts what had happened. As they did, the U.S. government was considering not immediately announcing that they had killed bin Laden, a U.S. official tells Time. But the Pakistanis, uncomfortable with having the information leak out slowly, “encouraged the United States to go public right away,” according to the U.S. official.
That's sort of interesting. Most likely, though, it wasn't so much that the Pakistanis "encouraged" us to announce the raid quickly as it was that they made it clear that the chances of keeping the raid secret were close to zero. Not only was there that downed helicopter in the middle of Abbottabad, but bin Laden's wife and daughter were in Pakistani custody, and word of that would almost certainly leak through ISI or other military sources almost instantly. At least, that's my best guess.