Hi Pete
Congrats on purchasing a DW board and welcome to the addiction of Downwinding, and I am happy to hit some DWers with you, although I don't do that many at the moment due to saturating myself in them all last winter and summer at the expense of family time. Family time is priority now, especially with another kid in the pipeline.
I know the feeling well as it was this same time last year when I made a purchase on my 1st board and also posted the same interest of looking for a crew in the eastern suburbs to guide a newbie in DWing in safety. All you want to do with a new/1st DW board is to see what it's all about and sink your teeth into it. I did not have too much luck either finding people in my area but had warm responses from the crew on the northern beaches, with Sam from Wind Surf and Snow including me in the "Sydney SUP Downwind" Facebook group. These guys seem the most active when it comes to doing DWers in an organised group, and there are also some guys from the deeper south, Sutherland Shire/Cronulla who get out too but do not make it known. I think I posted a run or 2 in my area and managed to meet a guy who lives around the corner from me at Botany.
Obviously Downwinding relies heavily on the weather/wind to line up, and for you to have the time/commitment whens conditions are on. I think sometimes these factors sometimes make it difficult for some people/groups to either commit, or post their DW runs, in this area anyway. In saying that, I still have not done a DW run with any of the experienced crews in Sydney as I thought initially I did not want to be a handbrake/liability for them when conditions are "on" and me being inexperienced.
For me, much has changed since a year ago and while I gave up on the idea of finding people in our area to go with, instead I spent a lot of time by myself on the water in various conditions getting my experience up. I do however encourage and support paddling and DWing with others rather than going solo, especially if people have a lack of general ocean/weather awareness and experience from other water sports.
SOME TIPS FOR WHAT IT'S WORTH THAT HAVE HELPED ME.
1.IF POSSIBLE ALWAYS PADDLE WITH SOMEONE ELSE, however sometimes this is not possible;
2. KNOW THE FORECAST FROM MULTIPLE SOURCES and learn to read the conditions and to constantly re-assess the situation;
3. BE CONSERVATIVE and only put yourself in situations that you know you can handle. Start small in bays and other more enclosed body of waters;
4. HAVE A BACKUP PLAN if things don't work out the way you hoped. e.g. this might be bailing out at Little Bay or Long Bay/Malabar or Coogee in an ocean DW run in the relative safety of calmer waters in the event of a wind change or a serious injury (touch wood).
5. TELL SOMEONE WHERE YOUR GOING and how long you will be and call them when you have arrived back at the car.
6. TAKE NECESSARY EQUIPMENT. If DWing or decent ocean paddling I always take a CO2 inflatable PFD, a phone, water, and a muesli bar.
7. GET FITNESS AND EXPERIENCE by paddling into the wind in increasing wind strengths for periods of time to see what you can handle in the event that you need to self-rescue yourself, or someone else (the misses). This adds piece of mind knowing that you can back yourself if needed. This might mean paddling from Bondi around the headland North into a north east wind for as long as you can, then DWing back to Bondi in relative safety. Malabar is excellent for this in both NE winds and a Southerly. These options are to prepare for a decent DW and are just lead-up sessions to get experience and fitness for the real DWing experience. General paddling in the ocean in calmer wind conditions is also very good around/near the headlands as there is backwash/cross chop that will all condition your body and will build your ability to be able to handle this type of confusing water.
8.THERE IS NO SUBSTITUTE FOR TIME ON THE WATER in a variety of conditions depending on your comfort level. Terminate your session when you are feeling a buildup of fatigue that prevents you from being fairly stable on the board, or move to more protected waters.
9. SEEK DJ's ADVICE FOR A MORE EXPERIENCED OPINION as he is the man!!!
We are about to come into some of the best times (for our area) for downwinders on Botany Bay with the consistent Westerly winds, and these are the best way to start out, and are pretty easy logistically and time wise.
Good options include:

Brighton/Kyeemah to La Perouse in a westerly (8kms)

Kurnell to Kyeemah in a southerly (9kms)

La Perouse to Kyeemah in an easterly which are not that common here but when it does come it's normally from a decent low out to sea and is cranking (8kms)

Rosebay to Watsons Bay in a south wester (4-5km)
Good Ocean DWer options that I have experienced in order of best experiences include:

Maroubra to Bondi in a southerly with a decent south swell (9-10km)

La Perouse to Cronulla in a northerly then back again on a decent southerly wind change (20km)

Malabar to La Perouse in a noreaster (8-9km)

La Perouse to Maroubra in a southerly (not recommended)
Other options that I have not tried yet but seem good are:
Bondi to Watsons Bay in a southerly
Bondi to Maroubra or Coogee in a noreaster
Hit me up, and I'm sure you'll get more advice from others who know more.
cheers
Potty