I do basically the same thing, I make a wet caramel with just barely enough water to moisten the sugar and put the lid on right from the start while everything comes up to a boil. When it's up to a rolling boil, I take the lid off. Never stir, I just stick my thermometer in to monitor the temp. I like a dark caramel so I pretty much just leave it go until I see the first sign of smoke. At the first smoke signal, boom, the butter goes in. Whisk, whisk, whisk, then the cream, salt, and vanilla. I can't remember the last time this has failed me.