after

1a. The movie starts at a quarter after six.
1b. The movie starts at fifteen minutes after six.
2a. You’ll get used to it after a while.
2b. You’ll get used to it after sometime.
Please correct the above.
Thanks.

2b does not work with ‘after’ where ‘sometime’ is a single word…
You’ll get used to it sometime.

It will work if you separate the word…
You’ll get used to it after some time.

This is because ‘sometime’ has a particular meaning.

1a/1b use of ‘after’ is AmE. In BrE that would be ‘past’.