Level Streaming at game start:

Level streaming is used in the creation of animated loading screens between the levels, but can we do that at game start?

Yes, you can.

Load an empty persistent level and have a level blueprint stream in the levels you’d like to have loaded.

To load that empty level takes 3 seconds i want before this 3 seconds to show some sort of an animated loading screen. There are games like Injustice that are loading directly loading screen, no this black start screen and they are using this engine.