I must admit this picture with titanic is really good and may be truthful.

When will be lisk start trading on exchanges?
Probably in the first week after the launch ( which is scheduled on 4th April if I'm not mistaken).
The launch is tentatively scheduled for April 11th, not the 4th. The April 4th date was for users to validate their generated keys. During this time, the devs are working hard to improve the stability of the network, they need to make sure the network is in perfect working condition.
Concerning exchanges, they should be available one to two weeks after the launch.
Edit: After discussing with oliver and max, the critical bugs found so far have been fixed.