The mannifera (brittle gum) have just burst into flower in the mountains south of Canberra this week, slightly earlier than in past years. I assume they will be flowering in the city too. Hopefully there will be some brittle gum honey pulled off frames around the region before autumn properly sets in!
On that note, and I will put this into the relevant thread in case anyone else ever searches for it, we have our first flowers on the E. mannifera post-bushfire. So to answer my own question - flowering seems to start around 1 year after a fire event, at least in some species of eucalyptus. Will keep detailed notes on our other 10 naturally occurring species as they eventually flower.