Vicky, the official answer is no. However, some people do have it with no effect (me included). Saying that, I only have a swig before bed. I buy a big bottle and it sometimes lasts me a fortnight. I never buy cans, becasue if I open a can, I will drink a whole can. Some people have a can a day - I personally would not risk it. You are in your first week too, so I would wait to have that little 'treat' if I was you.
So, officially no it is not allowed, BUT some people have it.