The period for earning MQM/MQS corresponds with the calendar year. The program year in terms of benefits is slightly offset from that (previously ended at end of Feb, now moving to Jan 31) with the caveat that you get your status as soon as you earn it.

So, the clear answer is that if you want Gold for 3/1/15 through 1/31/16, you need to make it to 50,000 MQM or 60 MQS by end of day 12/31/14. If you do make it to one of those thresholds, given that you already have more than enough MQD, your Gold status would be active within a few days.

If you do not meet 50,000 MQM or 60 MQS by 12/31/14, then you will be Silver through 1/31/16 (as you can already see) and will roll over the number of MQMs you have above 25,000. If you stopped today, you'd roll over 14,783 MQM. However, Delta does not provide MQS rollover, so it's back to the drawing board there. Also, note that you will have no rollover if you make Gold by reaching 60 MQS but your MQM stays under 50,000.