It seems to me that this is determined later about 2 months after the dividend is paid or even later. I have not seen any earlier report than that. So you just have to estimate it.
Also note the 61-day rule.
It's all about short-term opportunistic rebalancing due to a short-term change in one's asset allocation, uh, I mean opportunistic rebalancing, uh I mean rebalancing, uh I mean market timing.