I have no idea of a number yet today.    If my memory isn't mistaken, this is the past trend:
PP VII- 600 tix sold first 3 days, 294 tix sold over next 10 months
PP VI   700 tix sold first 3 days, 200 tix sold over the next 16 days
PP V-   700 tix sold first 3 days, 200 tix sold over the next 10 days
PP IV-  sold out in 4 days
PP III-  sold out in 6 days
I would be surprised if I haven't  hit the 700 mark after sales today (3rd day).   How fast it sells after that is anyone's guess.   I don't think any festival dedicated to these two genres are going to sell as fast as in the previous years regardless of lineup.   It is a different enviroment now as costs are higher for everyone and the big names are able to tour on their own in the U.S.    That has a major impact on the casual fan as they are the ones that impact quick sell-outs.   
While I obviously want the quick sell-out,  I have to be realistic on things.  A sold-out show should be looked at as a success regardless if it takes 6 months or 6 days to sell-out in today's market.