NSW and ROA do not have lineups in, so I might just sim GB vs NZ+ROW and wait until the other lineups are in.
If you want more activity, you should probly try and sim at around 7-8pm AEST. It's around 1 am now there. (mostly for the nsw match, but in general too)
TBH for this sim espeically I think it should be simmed at a time that is friendly for GB too. I would say most of the keen people are British and yes while you need to attract Aussies in too it would not be fair to almost punish the guys who started SR.