Just my opinion here, but if take a good look at the TBA calendar alone, it would seem that the only option would be to postpone this event until next year as you have the following events on between now and december.
SPC - This Weekend
Adult Nationals - Most of October
Sharp - Middle of November
Brunswick Adult - 1st Weekend of December
Brunswick Youth - 2nd Weekend of December
Keeping in mind that most people, after either the adult or youth brunswick cup, with league having finished, will take a break for 3 or so weeks until league starts again.
Then you have National Youth Cup and Youth Challenge at the beginning of January, I would dare say SA Cup at the end of January, so why not run the event say 2nd or 3rd weekend of February (around the time Mt Gravatt Youth was run).
And then after this it gets busy again with 2 tournaments in Perth in March, AO in april and then the rest of the majrs come in.
My Suggestion: Run it in the middle of february next year. You already have the format and entry form done, so you now have 5 months preparation for it as well, plenty of time to get your entries, people have ample time to book flights and it can become the tournament you want it to be.
My 2 cents
BTW, i would bowl this event in february if i hadnt already booked a trip overseas, but best of luck with it all guys.