3-4 years

https://backpack.tf/item/11578993127

Sale #1:

https://backpack.tf/profiles/76561198313722516#!/compare/1720396800/1720569600 ~ 1 ref 2 rec matches

https://backpack.tf/profiles/76561198311498888#!/compare/1720483200/1720569600 ~ cant trace

Sale #2:

https://backpack.tf/profiles/76561198169458269#!/compare/1720224000/1720310400

https://backpack.tf/profiles/76561198313722516#!/compare/1720137600/1720310400 ~ using here https://backpack.tf/suggestion/66a5e29228714bb63c00c536#comment-66b8efa986f06517070345cb

Sale #3:

https://backpack.tf/profiles/76561198141685007#!/compare/1720224000/1720310400 ~ no matches

https://backpack.tf/profiles/76561198169458269#!/compare/1720224000/1720310400

Sale #4:

https://backpack.tf/profiles/76561199073805105#!/compare/1718841600/1718928000 ~ 54 keys matches

https://backpack.tf/profiles/76561198141685007#!/compare/1718841600/1718928000

Sale #5:

https://backpack.tf/profiles/76561198027785685#!/compare/1718496000/1718582400 ~ 50 keys pure matches

https://backpack.tf/profiles/76561199073805105#!/compare/1718496000/1718582400

Sale #6:

https://backpack.tf/profiles/76561198840987606#!/compare/1717718400/1717804800 ~ 30 keys pure + Hammy (5.4) + Lone survivor (7.07) + Strange Doc's Holiday (10.25)

https://backpack.tf/profiles/76561198027785685#!/compare/1717632000/1717804800 ~ also added a Non-Craftable Professional Killstreak Tomislav Kit (instantly sold on the same day, also seen in the seller compare for 15 keys + 26.11 ref)

Making this 68 keys.

Sale #7:

https://backpack.tf/profiles/76561198045749377#!/compare/1717718400/1717804800 ~ no matches

https://backpack.tf/profiles/76561198840987606#!/compare/1717718400/1717804800 ~ ?

Sales @ 54, 50 and 68

With STN selling for 57, 68 is an outlier, taking 50-54

https://stntrading.eu/item/tf2/Unusual%20Morning%20Glory%20Gridiron%20Guardian // https://i.imgur.com/yTyx1P9.png