i would strongly recommend against it. i live on the west coast and it is nearly impossible to get flights with Avios these days. Club World seats do appear esactly 355 days out and they are snapped up immediately. You can't book onward flights on the same ticket because since it's the next day when you arrive in london, the seats are not released yet. We did manage to call up and get a very nice agent in the UK to add the onward leg with no extra charge other than the Avios. Usually we get put through to the call center in India whose agents are extremely difficult to deal with.
In short, it's extremely difficult to use Avios and I can't imagine having a million of them sitting there. I have a few hundred thousand and am regretting having them there.
i highly recommend that you do some very thorough due diligence before committing.