I would not recommend it if you don't have someone to help you take care of it. I currently am a 4th year student and have 2 dogs. We got the first one as a puppy during my 3rd year and definitely could not have done it without my boyfriend (especially during overnight call it would have been impossible). We live in an apartment with no yard so we have to be very devoted to 1-2 walks per day, dog parks, and dog beaches to get their energy out (which is HARD when you are exhausted after all day clinicals and just want to sleep!) . We also spend quite a bit of money each month on dog walkers that come 3-4 times per week when we are both working during the day. If you still feel the need to get a dog, consider rescuing one that's a bit older (2+ years). We got our 2nd one about 6 months ago from a rescue. He is about 2 years old and is the most amazing dog. He is so loving and calm and the transition has been very easy. He was fostered with a family for about 4 months when we got him so we knew how much exercise he would need, if he was housetrained, if he chewed, so that has been incredibly easy!
Good luck with your decision. Even though you have time now, make sure you also think about clinical years. YOu will need a lot of extra funds (food, treats, vet, walkers) and a plan for clinical years during overnight call, long days, aways, and interviews.