This build sets you up for a very strong economy and mid game transition. Also allows you to afford alot of sunkens for early defense.
9 Hatchery (2nd Hatchery)
9 Overlord
9 Spawning Pool
10 Hatchery (3rd Hatchery)
1 Creep Colony when the pool is 70% done
12 Hatchery (4th Hatchery)
15 Hatchery (5th Hatchery)
18 Hatchery (6th Hatchery)
17 Overlord
Add 2 Sunkens for defense
19-20 Hatchery (7th Hatchery)
26-28 Gas x4 – Build gas after you have around 6 Sunkens (~4:20 minutes)
@ 100 Gas → Build 2 Hydra Dens and 2 Evolution Chambers
Research Range + Speed + +1 Weapon + +1 Carapace
@ 250 Gas → Morph 2 Lairs
Transition
Drone up to 60 Supply before producing more units.
After reaching 60 supply, make 3-4 Overlords and wait until all Hatcheries have 3 larva available.
Hydras should start coming out by 6-7 minutes, depending on how many sunkens you built.
Notes
Sunken timing is crucial. If you're being rushed by Zealots, Marines, or Zerglings, you may need to increase the number of sunkens to 6-8. Do not take gas during this time.
Only build Hatcheries after you've spent all your larva. Manage your resources efficiently.
Send your second Overlord to your choke as soon as possible to scout for any incoming attacks.
After reaching 60 Drones, make 4-6 Overlords and begin Hydra production all at once. Do not build Hydras little by little.
Start Lurker upgrades immediately after Hydra Range + Speed research is done and add two more gases.
Push out with 18-24 Hydras and simultaneously build a Queens Nest and Spire.
Make 4-6 Lurkers and place them at your choke for defense.