TvZ 18cc basic guide

This guide assumes the following:
Zerg went 12h into a 2 hatchery build into 2:55 or 3:02 lair.

Goal of this build: Go into midgame ~6:00 minutes with a strong economy, defenses for muta, and pressure zerg to make ling/sunks on a stim timing at 5:00.
Why play 18cc?
It's a build that can be used on all maps in most situations. It's not dependent on first scouting zerg like with 15cc, and is safe vs all builds. How to deal with pool first builds is not covered in this guide.
It's important to understand that 18cc is flexible and can have many variations. A lot of it will depend on what zerg does, and what your personal playstyle preferences are.
Most important is to understand the order in which things are built-in.

Order is always rax cc (rax) gas acad ebay, but there are details that matter with respect to if you build more marines initially, or if you cut marines.

You have a choice of following up with 2, 3, 4 rax tech, as well as ebay first if wanted. You can play with a wall, though not necessary.

How to place turrets:
Calculate muta timing from lair timing. It takes 20 seconds to mine 100 gas, after which lair should start. From lair start time, you can add an additional 3 minutes to calculate when mutas arrive at your base. Add 10 seconds if cross position.
Example: Zerg first drone with gas returns to the hatchery at 2:32, then lair timing should be at 2:52, then muta is at your base at 5:52
Start turrets at ~25 s before muta come.
Turrets should be 2 at natural, 1 at ramp, 1 in main, starting from wherever is closest to zerg's base.
Example : Zerg spawns at 5, I spawn at 7 on polypoid, put turrets up in main first. Then add 1 turret at each location when these initial 4 are done. If it's a post 3 minute lair, you can delay turrets, but need to have 3 at nat 2 in main when mutas arrive (they'll have 7, instead of 5)

Build order, assume constant scv production unless if otherwise noted) 9 depot (:54) 11 rax (1:23) 12 scout 15 depot (2:12) @100% rax, if not 1st scout, send scv building rax to double scout @100% rax, 2 marines (if 1st scout, can go scv instead of 2nd marine). If 2 marines, you will cut half an scv due to supply block at 18 18cc(2:44) ,depending on build order, could also be at 19)

Choice 1:
This goes for the standard stim rush that leaves the base at 5 minutes. The easy way to remember this is to cut at 2 marines, then get 2nd rax, then resume marine production getting gas/acad when available. It is also fine to cut at 3 marine if you scouted late.
https://vod.afreecatv.com/player/100463343 9h39m
Cut at 2 marine
20 rax (3:03)
Make 1 more marine
22 gas (3:18)
Resume marine production
24 acad (3:40)
@100% gas, transfer 4 scv to natural, mine gas. This should leave with 1/patch in main.
30 depot
@100% acad, 2 medics + stim (should be at 7 marines now)
ebay when money is available (~36, ~4:40)
40 depot
42 rax
@100% stim, upgrade range
@100% ebay +1
place 4 turrets@5:40
@100% turrets 3 more turrets

Choice 2: You get a third depot while getting gas acad , then rax ebay. You do not cut marines, and can put marine pressure with 4 marines on zerg if they skimp on lings.
22 supply
25 rax (3:27)
transfer 4 workers to nat
3:50 gas
4:10-20 acad
4:45 ebay