head start

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun Sports A start before other contestants in a race.
• noun An early start that confers an advantage.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun idiomatic An advantage consisting in starting a competition or task earlier than might be expected; given (or taken), for example, prior to the beginning of a race.
• noun idiomatic A factor conducive to superiority and success

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun the advantage gained by beginning early (as in a race)