YOU SAID:
I am having dinner at 7 today.
INTO JAPANESE
今日 7 時夕食を食べています。
BACK INTO ENGLISH
I am having dinner at 7 o'clock today.
INTO JAPANESE
私は今日7時に夕食を食べています。
BACK INTO ENGLISH
I am having dinner at 7 o'clock today.
That didn't even make that much sense in English.