I need to estimate this too in terms of hedging amount and time.
First, I am assuming that there will be a sequester-related volatility in late February that will be about the same magnitude of the debt ceiling-related volatility in last December when spy was down 3.45% (145 to 140) and vxx was up 28.5% (28 to 36). Its ratio is about 8.25% that I may need to buy 8.25 percent amount of portfolio assuming that there will be a sequester-related volatility similar to the last debt ceiling-related volatility. Perhaps this estimate may be too simple with too much assumption but gives a guideline.
Second, most importantly, I need to figure out when I am going to hedge my portfolio. I believe this week we will see EUR/USD will be 1.33 to 1.34 and S&P 1515 to 1525. Perhaps it will be best to purchase vxx at S&P 1525 and EUR 1.34 for protection. It is hard to predict the exact time but we will see how markets move next week. In my opinion, I will purchase vxx on Friday or the following Monday, of course, it depends on headlines from Italian and US politicians.