Having to make a change to a JQ domestic flight that is 6.5 weeks from now. Will not owe a change fee due to fly flexible but last week the flight was just over 100 AUD vs. it now being 215 (vs. my original cost of 79 AUD). And I need to change 4 tickets.

Prices for the same day of week between now and then are a mix -- i.e. this week/next week would be about the same, but then it dips as low as 159 for a few weeks before going back up for my week and beyond. On EF it shows: Y9 B9 V9 T9 S9 R9 Q9 P9 O9 N9 M9 E9 F0 L4 A0 Z0 I0 K0 H0 X0

I want to confirm my new dates as soon as possible, but also want to minimize the additional cost (i.e. my hope is $200 USD or less in cost vs. the almost $400 it would be if I make the change now).

Any experiences to share? I have been watching this route for a while and even close in dates were much lower. I kinda of feel there is not any downside for waiting another week or two and will keep checking EF to make sure a sellout is not imminent. Then again it could go 100 AUD the other direction on me.