Jumping-off point and Zero hour

Jumping-off point noun - A beginning from which an enterprise is launched.

Zero hour and jumping-off point are semantically related In some cases you can replace phrase "Zero hour" with "Jumping-off point", this phrases are similar.

Zero hour noun - A time or state of affairs requiring prompt or decisive action.

Jumping-off point and zero hour are semantically related in moment of truth topic. Sometimes you can use "Jumping-off point" instead a noun phrase "Zero hour".