As wendall says, Advocate is primarily a worm treatment, specifically lungworm, which is also effective against fleas. Ideally it should be applied monthly to be fully effective. Giving a treatment a few days earlier than normal shouldn't present any problems though.
It's thanks to regular use of Advocate that our worker, Chaz, was able to shrug off a lungworm infection a few months ago without any further treatment other than his usual monthly dose of Advocate. The original infection was spotted by Wormcount and a more recent Wormcount test has shown him now to be free of lungworm.
Google on "Lungworm in dogs" for more information.
Bob.