According to NASA, it will take  "about 28.5 hours for the spacecraft to autonomously dock to the space station at 11:30 p.m. EDT Saturday, March 15, while traveling 17,000 mph orbiting the Earth."Once the crew successfully makes their way to the ISS,

The replacements for NASA’s two stuck astronauts launched to the International Space Station on Friday night, paving the way for the pair’s return after nine long months. Butch Wilmore and Suni Williams need SpaceX to get this relief team to the space station before they can check out.