I rode a timeless for 4-5 seasons and don't recommend it for a beginner.
It's fairly stiff and being 155 myself I felt that the 159 was too big for me. A great carving board but turn initiation can be difficult at times.
My board is obviously an older model, not sure what's changed over the years.
With regards to board size, someone on these forums put it this way: Your board doesn't know how tall you are, but it does know how much you weigh... so go by that.