Sometimes the names are there when I first start thinking about a story. Other times I have to search for them. In 'His Leading Lady' the heroine was always Jess, but it took me some time before I decided on Kyle for the hero. I wanted a Scottish name and tried a few others before finally deciding on Kyle. Once he became Kyle, he became real.
In my current story, the heroine was always Abbey (occasionally called by her full name of Abigail) but to begin with, I had no ideas for the hero. I called him Jack just to give him a name and intended to change it once I got into the story. But somehow he became Jack, and there's no way I could change his name now!
Actually I have far more problems with surnames. Surname books and internet lists are too long, so sometimes I flip through a TV magazine to give me a surname, or look along the line of books on my shelves, or even think of a name from my family history!
In the end, though, I think all names are subjective. There are names we like and names we don't (for whatever reasons), and of course other people have their likes and dislikes. The hero in one of my early books was called Max (short for Maxwell), and I remember my mother saying the name Max always reminded of a neighbour's dog which had a really annoying bark. Just shows that you can't please all the people all the time!