How to delay streaming world composition levels ?

Here is my situation. I need baked lighting and large level. World partition doesn’t support baked lighting and who knows when it will (definitely not in 5.5). So my choice is to bog down making some kind of streaming manager or use world composition (I am on 5.4.2).
I set up my world composition world and it works on mobile devices, but due to slow I/O it takes forever to load initial tiles, which is obviously unacceptable.
What I would like to do is to load a small level first (like a room or something, with a few things for player to do while waiting for the large world to finish streaming) and spawn player on it. After that I’d like to kick off loading of the world composition levels.
Is it even possible to achieve? If so, how? I didn’t see anything in streaming BP nodes in regards to world composition.