The islamic month of Shawwal 1439 AH (hijri) is marked by moon’s conjunction on Wednesday, June 13, 2018 at 19:43 UTC. This birth of the moon happens at night in major parts of the world. No moon sighting is expected on Wednesday.
In the evening of Thursday, June 14, 2018, the hilaal (young crescent moon) will be easily visible or visble with optical aids for most parts of the world. Only Japan and New Zealand will miss the moon sighting.
Therefore, based on moon sighting, globally, 1 Shawwal 1439 AH will fall on Friday, June 15, 2018.