Outside of last minute break downs etc, how long before a flight is an aircraft type locked in?
I booked a reward flight in J on VA469 (PER-BNE) for November. It chose this flight because it was an A330. A while later I got the email where they told me might flight time had changed 10 minutes. As it turned out this was because of an aircraft change. I logged in and selected new seats, because none were allocated automatically. I just logged in to my account to check my booking as my forward journey is happening soon. My booking is now appearing twice and it's again showing as an A330 with my 2 seats allocated as 5A and 5D. I'm travelling with my mum, and it would be preferrable to sit with her, but it probably doesn't matter a whole lot. My only concern is that if they swap it back to a 737 again, 5A and 5D aren't in business class at all. For some reason it's also showing that I have 2 bookings on the same flight. Both are showing as VA469 but they're showing as Flight 1 and Flight 2.
I know that that's a long way away, but this flight and the forward journey are actually positioning flights for overseas travel with another airline (with a very long stopover between them)