EDIT 1: Hold because of pneumatic checks. Next attempt will be on the 28th.
EDIT 2: Moved to the 29th. More time necessary to check pneumatic ground systems.
Delta IV Heavy NROL 44 Mission Profile
United Launch Alliance (ULA) is launching an unspecified satellite on a Delta IV Heavy for the [National Reconnaissance Office (NRO)](National Reconnaissance Office) from SLC-37B, Cape Canaveral, Florida to geostationary orbit (around 36'000 km).
Scott Manley talking about the particularities of Delta boosters:
Explaining the Delta Rocket Fireball
Check your local time of launch at: www.timeanddate.com
Where to watch:
Join Tim Dodd 30 minutes before launch for his coverage: Everyday Astronaut
Useful links to stay up to date on launches:
Spaceflightnow.com: Launch Schedule
Everyday Astronaut: Prelaunch Previews
Space News:
NASA Spaceflight nasaspacefight.com
Be aware, this is rocket surgery.
Small disturbances can lead to postponed launches. Making sure everything is just right is way cheaper than risking big fireworks.