Mystery Skin Giveaway

Hey, so according to this article "for every six mystery items you purchase for yourself or friends, you’ll receive a free Mystery Skin after the event ends!". Well i received a free Gentleman Cho'Gath skin today from Riot (very happy about that), but i know i bought at least 16 mystery gifts during the event, so I'm just wondering when I'll get my second (and maybe 3rd) free skin since it does say "for every six" and i met that requirement 2-3 times. Any information about the day they'll be given out would be appreciated! ^-^