Is there any news on when k=1000 will happen?
On December 06th 2020, IOHK increased the k parameter from 150 to 500. This affected the optimal number of pools in the Cardano network. This change lowered the saturation point for stake pools from 220M ada to 64M, resulting in the loss of some rewards in oversaturated pools.
Epochs 300...320 ?
At the moment there are >3000 stake pools. The Cardano network reached full decentralization and, apparently, very soon, the k parameter will be set to 1000, which will lead to a decrease in the saturation point from 64M to 32M per pool.
I think that you don't need to redelegate your stake at the last moment (when k will be changed). You are free to pick a new stake pool below 32M and you will not miss any rewards.