Hi! Both the event page on the forum as well as the event page in the game shows that the event period is between June 18th, 2020 to June 24th, 2020. The deadline to claim is June 30th, 2020 at 23:59:59. Keep in mind that the period is based on your server time and not your local time. So if the time is not the same, there could be a discrepancy there.

Here are some pictures for reference: