Ball pythons fast for a number of months, it all depends on that individual snake. Some go one month or less, some go a year. As long as it isn't losing considerable amounts of weight, there is not much to worry about.
What exactly do you mean your one year old BP just started climbing? That question kind of confused me, because I don't really know what you're asking. I have noticed my Ball pythons (all different ages) will climb when given something to climb onto. So if that answers your question, then there ya go.
Jennifer