I learned this build from Pluto AI. Here's the replay I played against pluto v2.0 (with extremely slow game speed).

Replay can be downloaded here: https://sagi.gg/game/3d1033fb-e6d0-f111-90d4-00155da89a1f

Build order:

8/10 - Supply Depot (0:51)
11/18 - Barracks (1:19)
12/18 - Barracks #2 (1:38)
14/18 - Refinery (1:58)
14/18 - Cut SCV
@100% Barracks - Academy (2:13), train 5 Marines
(Here I made a mistake, should build Academy first, then Marine)
15/18 - Supply Depot (2:23)
@100% Academy - train 2 Medics, research stim pack
Move out with 5 Marines, 2 Medics, 3 SCVs.
Arrived opponent's natural at 4:00, with stim pack just finished. It would take about 30 seconds for Protoss to have Dragoon range upgrade finished.

Zerg can simply deny this push by building sunken colony. For Protoss this push seems powerful even if scouted. Hard to defend before Dragoon range finishes.