If you don't have a road bike yet, then start there. You will get more use out of a road bike than only having a track bike. You will also need/want a road bike as your training progresses.
The roadie will allow you to train more easily by accommodating a much wider range of training .at the same time, for people who aren't racing super competitively, a road bike is more accommodating of variations in fit because the position is more relaxed.
When it comes to track bikes, the better you get at track, the more dialled in your position becomes, so it's best to buy into a track bike when you better know what events you will be focusing on, and how you want your bike to fit to accomodate this.
A road bike is sort of like a chef's knife. It's pretty good at doing most things in the kitchen very well, without toouch compromise. A track bike is more like a scalpel, having a narrow range of use, but doing what it's designed to do better than anything else.