Xbox One players can play the Miramar map in PlayerUnknown's Battlegrounds on Xbox One starting tomorrow. This was announced by the PUBG Xbox Team over on the official forums. The desert map will be downloadable in the Xbox Store by searching for the "PUBG Test Server".
The test servers will be online between at 02:00 CEST and 08:00 CEST in the morning from April 26-28, which means if you want to check the new map you'll have to play it late at night. During the weekend, that being April 28-29, the servers will be online from 20:00 CEST till 08:00 CEST, which gives you a better chance to check out Miramar.