Day Trading 16 Mar Pre Market, page-70

At 10:00am AEST, the market opens for ‘Normal Trading’, but on a staggered basis. By this, I mean that all ASX stock codes starting with A-B open at 10:00:00am (+/- 15 seconds), those starting C-F open at 10:02:15am (+/- 15 seconds), G-M at 10:04:30am (+/- 15 seconds), N-R at 10:06:45am (+/- 15 seconds), and S-Z at 10:09:00am (+/- 15 seconds).

from Rivkin

https://www.rivkin.com.au/blog/shar...e-asx-opening-and-closing-auctions-24222.aspx

I use an anagram to remember it - All Cute Girls Need Sweetness.