I'm so sorry to hear about your BIL's passing.
I think your sister probably needs a few days to decompress and handle her feelings,
so it wouldn't hurt to wait a bit to think about going out there.
If she knows about your job situation, she would understand that you can't do anything just yet.
After all, if there were to be a funeral, those take a few days to arrange, and even
a memorial service takes time to set up.
It sounds like you are pretty close with your sister. I think you'll be discussing things with her again soon.