Give virtual bitcoin/eth to users who register say worth US$10000. Let everyone trade against the real trading signals. It can be a week or 10 days contest and at the end who ever finishes top 3 should be rewarded 3000/2000/1000 COBs.
This will help in testing the exchange real time using virtual money. On the other side traders get familiar with the exchange and start immediately once it starts with real coins/fiat.