Porting of Priority Date from EB3 to EB1

Hi Rajiv and Team,

Thanks for the guidance. We want to know what should be the priority date for our case mentioned below:

1. I have an approved EB3 I-140 with priority date as Dec-2014.
2. Based on Eligibility, the same employer filed EB1C I-140 on Jan-2018 which was approved and have retained the earlier priority date of Dec-2014.
3. Now, the receipt of I-485 which was filed in March-2018 has Priority date of Jan-2018.

So our questions are

1. What should be Priority Date of my Case : Dec-2014 or Jan-2018?
2. I am from India. Is my case current based on the priority date and Nov Visa Bulletin?

Could you please advise?