Applying for TN1 visa and need advice.

I am a Canadian currently working and living in Vancouver. I just got a job offer from a US company in New York as accounting manager. The offer letter states start date as on or before Sept 15. I went to the Pacific crossing border last night and was told they cannot look at my papers or application until I'm ready to go on to my new job. I'm currently working and don't want to quit my job until I know for sure I can get the TN1 visa. I have an accounting degree from a US university and have more than 10 years of accounting experience. In fact the new job will be similar to what I'm currently doing in Canada except the title here is not manager. I was told by one of the immigration lawyer that accounting manager is not on the occupation list and it might get turned down when I try to fly out to New York on Sept 12. Has anybody experienced similar situation like mine. Any suggestion? I've contacted an immigration lawyer based in the U.S. and hope she will look at the paper work and tell me if they are sufficient. However, I was told by the custom officer that there is no guarantee and it is really depend on the mood of the officer that day. Hope somebody in this forum has similar situation and can advice. Can I drive to Washington border and try and get the visa and then spend a few days in Seattle and turn back to Vancovuer to quit my current job.

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