YOU SAID:
I don't know when to send you the mugs
INTO JAPANESE
マグカップをいつ送るかわからない
BACK INTO ENGLISH
I don't know when to send a mug
INTO JAPANESE
マグカップをいつ送るかわからない
BACK INTO ENGLISH
I don't know when to send a mug
That didn't even make that much sense in English.