When are the free mystery skins going to arrive?

I purchased 6 mystery skins on August 8th and was just curious as to when my free one will arrive? Would it show up in purchase history? Last time with the free champ I got Nami and she appeared in my roster but I did not receive the chest until 3 days later so I was very confused. This isn't a champ it's a skin though so it will be difficult to tell what I got this time haha XD? Are they already distributed so should I search all my champs, or will it take a bit longer?