How long does it take for a friend to use netflix?

I booked another package with netflix a few minutes ago. How long does it take for my girlfriend to use netflix?

What does another packet mean? Have Netflix myself and pay the price once a month. My parents also have an account.

You can use it right away. Does the account run over you as a 2nd account or does it have its own?

I have an account that is already being used by a second person. But the ultra hd packet says that 4 people or 4 devices can use it.