At the end of the two-to-three week period...you become contagious as you show fever (101 or better). No fever, no Ebola.
I would note this odd characteristic which popped up in some discussion yesterday. The survivors of Ebola (more each day) carry an immunity to Ebola. What wasn’t noted early on by the news media is that this immunity is only good for roughly a decade. So, you could catch this a second, third, and even forth time. No one much has talked this angle of the problem.