In reply to NickH85:
The huts are fully booked out at the beginning of the season and have been for many seasons. Punters rely on scheduled guided parties not being there. When we were there in Chamonix we just turned up at the huts. They were "fully booked up" as usual and my mate and I shared "we have left only one and a half spaces in the Gouter", it was the best they could do they told us. I remember when one person turned around to sleep on their other side, we all had to do it in turn. I was trying to sleep next to a Spanish guy with the scariest face I have ever seen, I got a fright every time I turned over to my other side, or when the wave was coming from his direction and he turned to face me. The snoring and farting was terrible, and in the midst of all this squalor, one randy French couple decided to have a quiet shag.....and others kept getting up to go for a hose or a dump. Don't expect to get much sleep! This was way back in 1997 and 1998. It may be more civilised now but I'm not sure. Lastly, we didn't buy the reciprocal rights card, but just showed them our BMC cards and this got us the reduced prices.
Your itinerary is adventurous, with a massive gain in altitude very quickly. I wouldn't hope for much chance of success until you can squeeze at least a week for it. Mont Blanc is such a special moment in your life it's worth giving it a chance, otherwise you'll be vomiting beside all the others and heading back down early. For every weekend warrior who flew into Geneva one day, summited the next day and flew home on the next again day, there's a sorry load of folk who found it too hard and didn't.
But don't let me put you off, just stay sensible and safe with your mate.
Tom two goes at Mont Blanc.