Basically there are just a few things you might look for once the feathers are coming along. At this age it is tough because the boys and girls really look the same. The males you would look at the combs and wattles to see if they are larger by comparison and redder than the other chickens...
I think the Aussie is a pullet, mine filled out quicker with their feathering than the boys did. I was thinking the GLW's legs looked a bit thick for a girl. Yes, 3 or 4 more weeks will really show you who is a hiding roo if you have one.
BTW, Congratulations on joining us crazy chicken folks!