flying start

1. Sports. A racing start in which the contestants are already in full motion when they cross the starting line.
2. A quick or auspicious beginning.

An initial advantage, as in His background in biochemistry gave him a running start in the field of genetics. This expression alludes to track events such as the running broad jump, in which one begins moving before reaching the actual take-off point. [1920s] Also see under get off the ground.

The noun has 2 meanings:

Meaning #1: a racing start in which the contestants are already in full motion when they pass the starting line
  Synonym: running start

Meaning #2: a quick and auspicious beginning
  Synonym: running start