Early July is the best time to do a status match to Delta airlines. If you have status on some other airline, you can get status on Delta just by applying.
For example, if you are Platinum of American Airlines you can become Gold on Delta. Or, if you are Premier Gold on United you can become Gold on Delta. According to the official rules a status match is a one-time thing and is good for 90 days, or all the way to January 31, 2018, if you meet the associated flight requirements.