5 months. 28.

Sale 1: http://backpack.tf/profiles/76561198272072941#!/compare/1487462400/1487808000 - Dapper is duped.

Sale 2: http://backpack.tf/profiles/76561198059767347#!/compare/1487808000/1487980800 - QS.

Sale 3: http://backpack.tf/profiles/76561198059767347#!/compare/1487980800/1488067200

Sold for a Clean Scorching Flames Triboniophorus Tyrannus (89 keys, clean one unsold for a month at 89: http://i.imgur.com/elF58ob.png ) + 1 key

89 + 1 = 90

Sale 4: http://backpack.tf/profiles/76561198172139053#!/compare/1487980800/1488067200 - QS 62 for pure.

Sale 5: http://backpack.tf/profiles/76561198172139053#!/compare/1488153600/1488240000 - QS for 51 pure.

Sale 6: http://backpack.tf/profiles/76561198057034390#!/compare/1488585600/1488672000

Sold for a Clean Massed Flies Heavy Duty Rag (12 keys) + a Clean Blizzardy Storm Rotation Sensation (44 keys) + a Clean Kill-a-Watt Rotation Sensation (38 keys) + 5 pure

12 + 44 + 38 + 5 = 99

Sale 7: http://backpack.tf/profiles/76561198057034390#!/compare/1488672000/1488758400 - Slug is duped.

Sale 8: http://backpack.tf/profiles/76561198211995121#!/compare/1488672000/1488758400 - Bulk.

Sale 9: http://backpack.tf/profiles/76561198211995121#!/compare/1488758400/1488844800

Sold with a Clean Smoking Furious Fukaamigasa (16 keys) for a Clean Nebula A Head Full of Hot Air (90 keys)

90 - 16 = 74

Sales: 90, 99 and 74. Going with a range of 74-100.