Help vs 8-8-8

I'm just wondering what the proper response to scouting an 8-8-8 is. I go 13 gate in PvT and it seems that even with constant chrono on stalkers I'm in a losing position, because I don't get the stalker out until he has 3 reapers on the map (assuming he goes 2 rax before orbital). Should I immediately grab double gas after scouting the cheese and get out a mother ship core? Am I supposed to grab a forge and cannon up my mineral line? Stalkers seem to get out just a bit too late.

Thanks, Lexor