From your post history it seems to me you're in the Netherlands. We are in a similar situation, with grandparents in NZ who are itching to spend some time with their 8 month old granddaughter. They had tickets for April which they moved to September, but I don't think they'll travel.

We have tickets on SQ for Christmas, and we're keeping an open mind, but I don't think we'll go. I think the worst part of the trip would be the quarantine at the end in a hotel room with two kids. If NZ had a self quarantine provision we'd probably go.

To go back to your question, if your plan is moving back to Australia, I'd go sooner rather than later. At nine months you could have a crawler in your hands (or on the airplane floor), the quarantine rules are not going to change from here to the end of the year (if anything, they'll get harsher I think), and if things really go south, I know I'd prefer to be locked down in a large house with a garden in Australia over in an apartment in the Netherlands in winter.

Stock up on masks and hand sanitizer and hope you're not sitting close to a superspreader.