Originally Posted by ISTFlyer

If the OP does the match now, he would be downgraded to Classic Plus in 4 months as he should take an international Turkish Airlines flight within 4 months after his match has been granted.
The best time to do the match, for the case above, would be September 2020, as if you do the match earlier, your Elite period would end earlier, if you can't make the 15k miles. Plus, a reminder that your first TK flight, in your case, AMS-IST won't count for the 15k miles as it counts as the "One TK international flight within 4 months" requirement.