Why do you want Army? Because SSO is a fast track? Or are you genuinely interested in the way Army does things as opposed to RAAF/Navy?
If you're simply after a fast track, put it aside and take an offer from one of the other services. No matter where you go, training is going to take time. However, if you're keen for the Army because you're green through and through, sell yourself to them.
Zulk nailed the RAAF/Navy mentality quite well. Who'd have it any other way?