As we now know the final individual prize requires 4000 sweaters, I made a daily collection chart that shows how many sweaters you should have by update time that day. This chart can also be found in post 3 on page 1.

Dec 21: 480
Dec 22: 640
Dec 23: 800
Dec 24: 960
Dec 25: 1120
Dec 26: 1280
Dec 27: 1440
Dec 28: 1600
Dec 29: 1760
Dec 30: 1920
Dec 31: 2080
Jan 1: 2240
Jan 2: 2400
Jan 3: 2560
Jan 4: 2720
Jan 5: 2880
Jan 6: 3040
Jan 7: 3200
Jan 8: 3360
Jan 9: 3520
Jan 10: 3680
Jan 11: 3840
Jan 12: 4000