Ann: Ceasing to be a substantial holder, page-142

If you read the underwriting agreement , you will find under section 5.6 Underwriting of Offer Shortfall , if this circumstance kicked in then the date of the notice might be seen with in 20 business days of the balance share sold.

(a) Subject to this clause 5.6 and to clauses 3.1 and 7, the Lead Manager agrees to purchase or procure purchasers for the Shortfall Shares and to pay or procure payment of the Offer Price for the Shortfall Shares against delivery by no later than 2.00pm on the Settlement Date.

(b) Without derogating from the Lead Manager's obligation to pay or procure payment of the Offer Price for the Shortfall Shares, if and to the extent that the purchase by the Lead Manager of Shortfall Shares is limited by applicable laws or regulations, Westpac agrees to retain any Shares above that limit (Balance Shares), the Lead Manager must procure purchasers for those Shortfall Shares as agent for Westpac in the ordinary course of its business, and Westpac must transfer those Balance Shares to settle those sales on notice from the Lead Manager.The Lead Manager may issue a notice under this clause 5.6(b) on more than one occasion,provided that the sale of any of its Balance Shares must be effected prior to 7.00pm on the date that is the twentieth Business Day after the Crossing Date, with settlement to occur no later than the twenty fifth Business Day after the Crossing Date.Nothing in this agreement gives the Lead Manager any interest or relevant interest in, or rights in respect of, any Balance Shares, except to act as agent for Westpac in procuring sales for the Balance Shares.

Timetable (clause 4.1) Key Dates for the Offer
Announcement Date 21 October 2020
Bookbuild Date 21 October 2020
Crossing Date 22 October 2020
Settlement Date 26 October 2020 (+ 20 /+ 25 everyone can do their math here)