If your going to use bollinger bands with Iron condors, then you are trying to time the iron condor with a spike up in the vix index. The idea is the "sell the iron condor" while the option prices are high. (sell high- buy low) The bollinger bands provide a nice "guidepost based" on standard deviation.
This makes it easier to determine when short term volatility is likely higher than normal. High volatility = higher option prices.
This is how I would do it anyway...
Best of Luck!