The next rebalance for the major indices happen in September,...

The next rebalance for the major indices happen in September, see the table at the following link:
https://www.marketindex.com.au/rebalance-announcements

Looks like notice is given 2 weeks prior for the September rebalance. Based on this announcement, it looks like notice is given around the start of the month, then the actual rebalance occurs mid-month.
https://www.marketindex.com.au/site...ements/rebalance/2017-rebalance-september.pdf

Fatman8 - you also wouldn't really skip the 300 and go into the 200, you would just end up in both (great result as more buying required by different funds!). If we only get the 300 in September, we might benefit from the 200 in December with continued growth.