I would suggest not being in a huge rush - the area generally used by JQ was originally set up to service a few TurboProps; now JQ are using it, it is not a very nice area with limited seating, little space and a generally poor atmosphere. ("Cattle Yard" comes to mind.)
The terminal building itself will be closer, however the actual gates itself is actually further away, even further away then the current T4 gates. I've attached a diagram to show you:T4 entrance is effectively moving about 100 metres north (IIRC will be connected airside with T3).
No more than a 10 minute walk from the QP.