Reason for launch scrub
The first attempt on the 27th of May was scrubbed due to bad weather at the launch site. The next lauch attempt is on the 30th because the lunch window to the ISS is instantaneous and the next favorable alignment will be at the end of May. It is an instantaneous window because this mission doesn't just go to a particular orbit but needs to meet the ISS on orbit. In order to reach the station efficiently, it is required that the spacecraft launches when the ISS passes over the launch site. From this point on, Crew Dragon will follow station while gaining height until rendevouz.
The SpaceX Demonstration Mission 2 will launch American Astronauts from American soil on an American rocket to the International Space Station since the last flight of Spaceshuttle Atlantis in 2011.
The booster is a new Falcon 9 carrying a payload mass of 12 t.
The rocket will launch from Kennedy Space Center in Florida and the first stage will land on a drone ship 500 km downrange in the Atlantic.
Travel time to the ISS will be 19 hours. Soyus capsules on their fastest track reach station within 4 hours. This mission takes a lot longer because the astronauts will be performing many check-out maneuvers along the way.
A collection of helpful YouTube videos:
Mission Timeline: Tim Dodd
How do Capsules work: Tim Dodd
Interview with Elon Musk and NASA Administrator Jim Bridenstine shortly before the first launch attempt: Tim Dodd
Milestones along the way to Crew Dragon
On the road to launching humans on their flight proven Falcon 9, SpaceX had to complete a myriad of additional certifications. Among them the Uncrewed SpaceX Demonstration Mission 1 to the ISS.
And the spectacular SpaceX In-Flight Abort Test: Nasa Video
Complete 6 hour broadcast of SpaceX's first launch attempt and background information: YouTube
Information about previous SpaceX launches: Wikipedia
Where to watch:
Tim Dodd will be live streaming a considerable time before launch: YouTube
Scott Manley will be hosting a live stream: YouTube
SpaceX Livestream: YouTube
NASA TV Livestream: YouTube
All streams will start a considerable time before launch. Check it early for updates.
Check your local time of launch at: www.timeanddate.com
Useful links to stay up to date on launches:
Spaceflightnow.com: Launch Schedule
Everyday Astronaut: Prelaunch Previews
NASA Spaceflight nasaspacefight.com
Be aware, this is rocket surgery.
Small disturbances can lead to postponed launches. Making sure everything is just right is cheaper than risking big fireworks.