
Firstly, have a look at every aspect of her life: is there any big stress there? She's had 3 homes - why? Does she have any issues?
I see so, so many dogs that pull like trains purely out of stress - it's not bad behaviour, it's not poor training, they are simply worried and want to get where they are going or check everything out NOW so can't even think about walking nicely. That's the case even if they aren't a nervoius wreck ;-) After only 2 days she may well still be very stressed out by changing homes again - the pulling will likely settle down a bit by itself as she settles in.
That said, then I recommend the 300 peck method of leash training. Easy to do, fun, and very effective, and explained perfectly here:
http://www.pawsitivelydogs.co.uk/300peck.pdf