Next Button State is Normal at Beginning of Timeline

There are 2 ways to restrict the learner from just clicking through the slides. 1 is to lock the next button by going into the player in the top tool bar, then click on the litter gear under the menu and change the Menu to Locked. This will lock the next button until the timeline finishes. The other method would be to use 2 triggers. 1 to hide the next button when the timeline starts and the other to show it when the timeline ends. The first is a global setting, the second needs to be done on each slide. 

Good luck