Thanks all, any tips for finding business class seats?
BA guarantee 4 business class seats on every flight which are released 355 days before departure at midnight GMT (so 1am in summer time). You can book the outbound online when its released (make sure you select your companion voucher when doing this). When the inbound is released you can either call up and get it added to your existing companion voucher booking, or you can book the inbound online (make sure you apply the same avoid/fees combination when paying) and request afterwards that BA refund 50% of the avios to reflect the use of the companion voucher on the outbound. The downside of the latter approach is that you need to have twice the amount of avois available in the account to be able to initially book and you will have two separate reservations so its a bit more expensive if you need to cancel.
If you want to secure seats on the most popular routes (Singapore, Sydney, Maldives, Tokyo), especially at peak times of the year, you're probably going to need to book at 355 days out.
If you're not willing to do that (admitedly its a bit of a faff and not for everyone) then you have to be a bit more flexible in terms of where you want to go. As long as you're booking 10-12 months out you'll have a long list of options. For example looking at next January I had a quick search for half a dozen destinations and can see decent availibility for 2 seats to Jamaica, Santiago, Mexico City in business class and it's a good time of year to go to those places. In contrast there is nothing avaiable whatsover for Sydney.
Generally the US has lots of availbility, particularly the north east, so you can afford to book a bit later.
As another tip is you don't need to fly to/from the same destination when using the voucher, provided that the distance between your arrival and departure airports must be less than the distance of the flight back home. So if for example you can only see outbound availability to LA, but inbound availability from San Diego, you could book both flights using the companion voucher. It costs the same as a normal return. You need to call BA to do this though as it can't be done online.
Finally, the companion voucher opens up business class avios availibility that you can't see through the Reward Flight Finder tool or Seatspy etc. This is a really good perk as BA release a surprising amount of extra seats this way. Unfrotunately the only way of finding this availbility is searching manually on specific dates on the BA website after having selected your companion voucher.
