I'm amazed this hasn't been implemented yet. There seems to be strong demand from the user community for it but complete radio silence from ESRI. Please implement this functionality as it would be a massive help.
Still needed. Would love even an "under consideration" flag. @AlbertSchelin saw your article on Dashboards in Enterprise, do you have any visibility on this?
I also need this. I just tried to implement it using a "Category Selector" that can select among the available times on the map. But it is not working yet. I hope there was already a time slider available. Until then, I will keep working on my workaround with 'Category Selector.' Please let me know if you also have come up with this idea. I will probably post a question if I cannot figure that out.