Hi Dan,
I can think of one way of doing this is that you set an element visibility:hidden from CSS panel.
So, for the entire animation, you can't see the element.
Insert a timeline event marker (a diamond icon) at where you would like to have the element appear, then set the event by double-clicking the diamond.
page1>event-1>Set styles>your element id>, at configuration, add visibility:visible and set NO easing. In this way, when you preview the animation on a browser, the element suddenly appears at where you set visibility:visible style.
I don't know if this helps to achieve what you try to do, could you try it and let me know?
Thanks,
Mariko (GWD team)