As stated in the Terms and Conditions:
Terms & Conditions
In order to earn TrueBlue points for shopping on Amazon, you need to sign into your TrueBlue account and use your unique link. Once signed in, you can earn 3 TrueBlue points for every $1 spent on Amazon on any eligible item. To see list of items excluded from earning points see above. Points will be posted at least 60 days after the item is shipped.
It says "at least" and not "within" so unless this is what it said all along, they might have changed it. This also means that it definitely will not post until at least 60 days have passed since shipping.