I will present a situation here and you can see where you stand right now..
You applied on 19th December, i will say you have 100% chance of getting visa before 6th jan, but then what? You will fly the very next day? No you cannot, because you need to submit you passport and they will print visa on it and then they will post it back to you, and thus process takes at least 5 days, so how many days do you have when you applied visa - 15 days because 25th, 26th and 2st will be a holiday (19 dec- 6th jan), embasy says they require minimum 20 days to process visa + 5 days for printing which means you are short on 10 days, now the possibility of you Landing on canadian soil in January according to me is 40%