Make sure that it's open and you can ride it before you plan a trip around going.
Also, I'd suggest making some sort of plans for the rest of each day. A velodrome is a lot like a gym in that it's great for using it for which it is designed. After your workout, there's nothing to do.
So let's say you do a 3hr workout (counting setup and breakdown), what are you gonna do the rest of the day?