My advice would be to claim one. When you do your taxes next year, you will see how much you owe or get back as a refund, and will be better able to gauge whether you could increase your exemption on your W-4 to two. If you do two now and owe a lot in taxes come next April, 2018, it will not be good, so try one for now.
Also, the IRS only allows a tax deduction for the interest paid on your student loan. There is no deduction for the principal portion of the $350/month payment.
