
Hi,
I suggest you buy a copy of 'The Rescue Dog' by Gwen Bailey. Your lab may not be a rescue, but it's very different taking on an older dog rather than a small puppy.
Basically, though, until she has settled in you should treat her very much as you would a small pup - because she is in a new and strange environment just like they are. Give her several weeks to settle in, and don't let her off the lead outside your garden until she knows where her home is.
Why is she being rehomed at this age? Perhaps you could register as a member with us and you'll be able to ask more questions.
:)