The Profile stats are a bit special. It's mentioned a bit discreetly under trial that it might not start updating properly right away when activating a subscription. Everything else should work straight away though (within minutes).
It hasn't been our intention to hide this fact, it's more that we haven't had a good place to put such text at. Also, we are planning to change the behaviour, but the work was interrupted and we started to work on other things instead. It will be fixed at some point.
If your date in the header of the profile stats becomes older than 8 days, please submit a ticket to Project-GC's support and it will be investigated. But I would assume that you will get an update soon.