H1B with B2 visa

[sp186]

I have an H1B visa (valid starting in March 2014) and also a B2 visa (valid until 2018). If I try to enter the US before my H1B starts, using my B2 visa, what should I expect to be asked at the border regarding the presence of the H1B visa on my passport? H1B is a dual intent visa and B2 implies I have no intention of immigrating to the US. So how can I reasonably explain to the CBP that even though I have a dual intent visa (H1B), I don't intend on immigrating to the US? It obviously doesn't help that my H1B is valid in less than a month.

Opinions?