10,000ITC International Tonnage Convention Endorsements

Good Day To All, I currently hold a 3rd Mate Unlimited License now and will be eligible for the 2nd Mate here shortly. So my question is once I receive 2nd Mate I will submit that day for the Cross over Exam from 2nd Mate to 1600T Master now here the tricky part. I been working on a vessel over 6000 ITC ( international Tonnage Convention System) so when I apply can I apply For 1600T Master w/ 10,000 ITC or I have to hold the 6,000 ITC before I can get the 10,000??? Being that I have the required Tonnage and timeā€¦
Thanks in advance from your sailing brother!