Resuggestion, thanks to K1ng for the info!

Sale 1:

https://backpack.tf/profiles/76561198201321490#!/compare/1534982400/1535155200

https://backpack.tf/profiles/76561198156577910#!/compare/1534982400/1535068800

Can only trace 4 keys

Sale 2:

https://backpack.tf/profiles/76561198156577910#!/compare/1535673600/1535760000

https://backpack.tf/profiles/76561198160856661#!/compare/1535673600/1535760000

Bulk.

Sale 3:

https://backpack.tf/profiles/76561198160856661#!/compare/1535760000/1535846400

https://backpack.tf/profiles/76561198176297517#!/compare/1535673600/1535846400

Bulk.

Sale 4:

https://backpack.tf/profiles/76561198176297517#!/compare/1535846400/1535932800

https://backpack.tf/profiles/76561198134512576#!/compare/1535932800/1536019200

Sold for 9 keys

Sale 5:

https://backpack.tf/profiles/76561198134512576#!/compare/1535932800/1536019200

https://backpack.tf/profiles/76561198161216801#!/compare/1535414400/1536019200

Untrace.

Sale 6:

https://backpack.tf/profiles/76561198161216801#!/compare/1536019200/1536192000

https://backpack.tf/profiles/76561198157102600#!/compare/1536019200/1536105600

Sold for 8 keys

Sale 7:

https://backpack.tf/profiles/76561198157102600#!/compare/1536192000/1536278400

https://backpack.tf/profiles/76561198127028869#!/compare/1536192000/1536278400

Sold for Blizzardy Pure Tin(8) + ~2 keys in sweets

Total is 10 keys

Sale 8:

https://backpack.tf/profiles/76561198127028869#!/compare/1536192000/1536278400

https://backpack.tf/profiles/76561198173708575#!/compare/1536192000/1536278400

Sold with ~1 keyin sweets for Blizzardy Panama

Panama Mini:

https://backpack.tf/suggestion/5ba7ce1dcf6c7562de748772

Suggestion for 12 keys

Total is 11 keys

Sale 9:

https://backpack.tf/profiles/76561198173708575#!/compare/1536364800/1536451200

https://backpack.tf/profiles/76561198112294568#!/compare/1536364800/1536624000

Sold for ~10 keys in pure

Total sales @:

8, 9, 10, 10, 11

Considering 8 & 9 sold quick,

taking 10 - 11 keys

K1ng's Part:

The 20 ref in sweets from sale 8 make it round to 11.