打算读PhD的MS签证问题疑问

各位好，我申请的是PhD项目，后来学校给录为了MS。拿到了RA，教授希望我一学期后转为PhD。
我的问题是，我在签证面试中关于学习计划和How long will you study in USA的问题，能不能说
I will study in the USA for about 5 years.  I like research and my professor want me to have a PhD education under his supervision. So I will switch to the PhD program when I arrived at xxx. And after I get a PhD degree, I will come back to China and find a position in colleges.

还是我直接说 I will have a master education for two years.等他问我是否读PhD的时候再说我想读PhD？

谢谢。