The best way to learn proper English is to read news report, and watch news on TV. Watching TV shows is a great way to learn casual English, slang words, understand culture reference and humor. If you have already watched these shows then you may recall the words used in the following dialogs.

The war against my sister
has already BEGUN.
Game of Thrones Season 7, Episode 3

Well, I had just BEGUN puberty...
The Big Bang Theory Season 8, Episode 23

And it's already BEGUN.
Westworld Season 2, Episode 2

Logan:
It's BEGUN.
Westworld Season 2, Episode 10

Okay, the NASA website says
Howard's final descent has BEGUN.
The Big Bang Theory Season 6, Episode 4