The only think so far I know you can do is to avoid the first scene/panorama of your tour to spin until you/the viewer decides to do.
For this: under the "publish settings" and there under the "general" tab you have to uncheck the "autoplay". This works only for the first scene of the whole tour and only for the first time. Once you return to that first scene manually (hitting a thumbnail or the combo box or similar) the scene/panorama will spin automatically again, as well as any of the other panoramas of your tour. A work around would be to load a still image as first scene to give enough time to load the tour.