That is not bad at all, given no prior training, and the fact that you have 8 months to do this.
The track can be kind of intimidating because there are strict times, you can see the finish line that never seems to get there as fast as you want, wind is always a factor, the curves zap your momentum etc.
Once you get your couple of months in with jogging with your dog, spend some time on the track. This familiarity will pay big dividends, even if you are just jogging.
Don't be afraid of this distance.
When I was training for the mile back in my early 30's, I was deathly afraid of the track. I started running 8 sets of 1:15 quarters with a quarter of walking in between and was absolutely gassed doing that only once a week. After about a month, I was still gassed but I noticed, I was no longer running those 400s at 1:15 but at 1:07-1:10.
Then about at that same time, my Tuesday running group decided to to do timed 400's kind of like a race, and I ran my 400 at :58 and it didn't even feel like I was breathing hard. From that point on, I no longer feared the track, but looked forward to track work outs, because I saw the positives in it: Which are: 1. You can run at close to your maximum without having to worry about saving it for later. 2. You can take as much rest as you need before the next go. 3. You will actually get faster during the workout. 4. You can scale up or down to the 800 or 200 very easily. 4 It is a quick run and you can adjust for any tactical failures in subsequent reps. 5. You actually get better at that distance very quickly.
Training for the 400 should be really fun. In fact, I wish more people would make resolutions to run faster and better rather than, say, train for the 10K or marathon.