It takes up to thirty minutes to update. You can post on the exact day or anytime in the two week period to get your points, though make sure the new period has actually started with the times in the op.
Thanks for that I wasn't quite sure whether I had to post on the day but I did notice after making 2-3 posts my activity did update so I should allow 30 minutes for it to update next time and not panic that my account was broke.