I assume your flight will be on a 737? If so then I think the only row that has basinet fittings is row 1. This row is usually only available for general selection from 80 hours prior. Top status (P1 and CL) can pre allocate these seats (>80 hrs) and Platinums and lower can only pre allocate row 2 and 3 (sometimes only row 3). So, without being an apologist for QF, your chance of getting into row 1 may be slim. I am unaware of the 48 hour prior for requests. Others may know more on these assumptions and may be able to clarify or give corrections. I don’t know how basinets are accommodated in the J A330 seats. Likewise I cannot visualise how basinets are accommodated in the 737 Y cabin - if at all (I know you have J tickets).
Flight is scheduled on A330. We booked this trip purely because of the wide body plane, thinking it would be easier to have more space, and twin aisles with a 5 month old. We are really hoping it doesn't get changed to the 737, but that is out of our hands.
You are right, I am not sure where I got the 48 hour window from. It is 80 hours. I have set an alert to check seat selection at T-80 hours.
Thank you for your reply, and for the reminder of the T-80 hour seat selection!