YOU SAID:

I forgot to tell my mom that I might not be home until 4:00

INTO JAPANESE

私は4時まで家にいないかもしれないと母に言うのを忘れていました

BACK INTO ENGLISH

I forgot to tell my mother that I might not be home until 4:00.

INTO JAPANESE

私は4時まで家にいないかもしれないと母に言うのを忘れた.

BACK INTO ENGLISH

I forgot to tell my mother that I might not be home until four.

INTO JAPANESE

4時まで家にいないかもしれないと母に言うのを忘れていた.

BACK INTO ENGLISH

I forgot to tell my mother that I might not be home until 4:00.

INTO JAPANESE

私は4時まで家にいないかもしれないと母に言うのを忘れた.

BACK INTO ENGLISH

I forgot to tell my mother that I might not be home until four.

INTO JAPANESE

4時まで家にいないかもしれないと母に言うのを忘れていた.