When is it time to export?

I’m designing a video game which is being modeled in blender but then exported to Unreal. Modeling wise everything is done, but I wonder about the next steps like animation. (Some people say Unreal can’t be used for animation.)I’m not even sure if objects can be reshaped in Unreal.(Noob). I know its best to UV unwrap in blender but use the Unreal editor to add materials. I suppose the main question is, at what point do I stop using Blender and turn it over to Unreal?