Sorry, I worded that badly - I missed an "over" out of it, so it should have read "and definitely before it gets OVER 7deg"

I mentioned in an earlier post that winter tyres work better at temps under 7deg, so it's fine to use them in the dry when it's lower than 7deg, but change back to normal tyres when it's higher than 7deg.

I've done the same as you - got a tatty/scabby set of spare alloys, with the winter tyres fitted, and just jack up the car and swap them over. It's quicker and easier, and also means you only have to pay for the tyre fitting once, rather than fork out twice a year to get the tyres swapped on the rims (and also, I think it's better to store tyres when they are at pressure, than store them off the rims? Could be wrong, sure I read that somewhere though)