Rankings are only updated every day or so, so just wait. I started today ranked #628 and I am still at that ranking despite all the posts I have made today.
Ignore my link, I thought you were asking about something else.
Yes, the cache can sometimes take a few days to update, considering that the site has to account for every point gained by every user every day. That means there's a lot of shuffling, especially in the lower ranks, when people gain a bunch of points in a short amount of time.
