[H] how can I cut reapers in tvp without dying to dts

I am a diamond Terran who has trouble in tvp, In Day[9]'s recent daily on Maru he featured many builds were the engineering bay seems to finish around the 7:30 minute mark. In the first of these games Maru skips a reaper but still get a scout of the gas of protoss off. I was wondering when is the earliest a 1 gas expand into dt build can hit you and is Maru's build safe against such a play. I know most dting players go 2 gas but on ladder I encounter alot who go one gas to mislead your scouting. How do you deal with this kind of play without a reaper to sniff out a fast twilight council/ shrine with such a late engineering bay?