Open with standard forge expand, then:

20 Gas, Gas

26 Core

28 +1 Attack

32 Pylon, Warpgate

35 Pylon, Zealot

38 Stargate

(Chrono Boost Warpgate and the Zealot, all before this was on probes)

Zealot

(stop zealots at 42 for a bit)

46 Gate, Gate, Gate

(Chrono Boost Warpgate and Zealot)

Pylon, Zealot

48 Voidray

51 Gas, Gas

+1 Armor