https://news.usni.org/2016/02/18/west-u-s-navy-anti-ship-tomahawk-set-for-surface-ships-subs-starting-in-2021 https://www.washingtonpost.com/news/checkpoint/wp/2016/02/18/report-u-s-ships-and-subs-to-receive-anti-ship-tomahawk-cruise-missiles/
No, its measured in minutes and starts when the satellite detects the launch.