Terjemahan:Saya makan malam dengannya pada bulan Januari.
This is a bad English sentence. You don't have a dinner, you have dinner. If January is in the future then it should read "I am going to have dinner with him in January', if January is in the past then ' I had dinner with him in January'. However dinner does not mean Makan malam. Dinner is the main meal of the day and can be eaten at any time. In the UK we have dinner hour and dinner ladies at school and this happens at midday.