By the time / The next time

I have questions about 'By the time/ the next time etc.

I I would really appreciate your answer if you could answer my questions.

I wonder if the expressions 1 through 9 are grammatically correct.

1. By the time we reached home, it was quite dark.
2. By the time that we reached home, it was quite dark.
3. By the time when we reached home, it was quite dark.
4. The next time you see him, please tell him about it.
5. The next time that you see him, please tell him about it.
6. The next time when you see him, please tell him about it.
7. Next time you see him, please tell him about it.
8. Next time that you see him, please tell him about it.
9. Next time when you see him, please tell him about it.

I wonder if the expression ‘by the time’ means the same with ‘by the time that’/ ‘by the time when’

I wonder if ‘the last time or the first time’ means the same with ‘the last time when’ / ‘the last time that’ or ‘the first time when’ / ‘the first time that’

I wonder if I can omit ‘the’ in the expressions ‘the next time, the next time when or the next time that.

Please reply.