Once your on the M2, you can't miss the M7 as it funnels you straight onto it (you actually need to exit at Seven Hills to miss the M7).
Once your heading along the M7, keep going to the end (the last exit is the Prestons turn off, and there is a massive Pallet suppliers building painted very brightly (left) and also the new Aldi distribution centre (right) - these are massive, if you miss them, don't bother at win coz you won't see anything).
Once your tag beeps, keep going straight, don't take the far left lane or you end up on the M5 heading east.
The next exit is Camden Valley way, I would keep going to you reach Picton Rd (Parachute jump site) and that takes you all the way to the top of Bulli by-pass and your in Wollongong.
Travel time I'm not sure about, but it's roughly 25 mins from M4 to M5 and then about the same maybe 30 mins to Picton Rd. From this turnoff, it will take you another 30 mins to Wollongong.
So approx 1 hr 25 mins + travel time from where ever you are on the M2 to the M4 (overpass).
Hope this helps, and you think of me whilst I'm sitting at a 21st