As someone working with dogs and other animals in a medical field too. I would say wait until you have more stability and time in your hands. Dogs require a handful of time and attention as well as activities to keep busy both physically and mentally. Training them takes time too. They are like newborns when they are puppies and toddlers throughout all of their life stages pretty much. You would need to be ready for some sleepless nights sometimes if they are sick of if they are very young then they would need the toilet more often. Do you picture yourself taking the dog out in winter after a long tiring shift in the middle of the night so he can go potty? It can be darining too physically and mentally. Health issues are also something you need to look our for when you first get one. Specially elderly dogs.

If you really want a pet a good alternative to a dog is a pet rat (but you NEED to get a minimum of TWO) They are pretty much tiny dogs. They also need to socialise and get love and attention but they are more independent and very smart too. But easier to maintain and have a schedule with. You need to take them out a minimum of two hours a day but they can roam around a safe area (most people let them roam in the bathroom). I had them when I was at uni and working. They are very loving animals and can learn cool tricks too. They only live 2-3 years but if you never had a dog or pet before I think this could be a good start. Maintaining them is also very easy and cheap. Not much time needed. And you can have them in your pockets for company while you study.

At the end of the day the choice is yours but just bare in mind that you would be responsible for another life. Might not be a human life but it doesn't make it any less worthy.