I logged in downloaded the first 4GB then closed and relogged and it gave me a HS installation confirmation and then downloaded another 4GBs,
I've relogged a few times since then and gotten no other prompts so I assume I'm up to date and just checking every now and then as the day goes on just encase they sneak another one in there.
My auto-install expansion option was already set to on when the new launcher was downloaded so maybe double check that is on under the config button if you have an issue getting the second one going.