jib - I've found this forum very helpful, also helpful to remember that humans have been making beer and wine for3K+ years, so it can't be that hard.
I agree that MalFet's "what do you want to do by racking" is a good question for Beer,
In the case of your wine kit however, I'd say follow the directions that came with the kit. If it doesn't say 'you should rack when the gravity is between 1.000 and 1.004' or something like that, then Bull's suggestion of 'if it is below 1.010' is good advice.
While you can be a little loose with the kits following their advice is generally agood idea because they have made that exact kit several times to keep it to get it 'right.'
Learn how to use the hydrometer it is your friend.