Except Google, no one can say that exactly. But we can guess, generally it comes in every 3/4 months. So, there is a possibility in last week of August or first week in September.
I guess, the update may be according to this : Next PR update As per the previous update records, Its around 20 days to it. I hope a best result. (y) It shall be a great news for us who sell links according to PR
Considering recent patterns of updates, there's no cause for concern unless we get into October without an update.
No one have the Exact same answer for this query...Because no one knows the Exact Answer of this Question... only Google Can say that When Will PR update
No one can answer your question exactly. It all depends on Google's algorithms which they have developed to get the PR of a site and moreover these algorithms keep o changing to punish the people who uses spam techniques to get rank. You could update anytime. May be right now also.