Funny, in November, two of the LHBS's I frequent were warning us that onestep should not be used anymore, especially for bottles. I don't know which group or agency was making that recomendation but they were both telling their customers to swtich to idophor or starsan.
It really is about the number of colonies of nasties it kills....Onestep's kill ratio is not high enough to qualify for FDA approval to be called a food grade sanitizer.
The official definition (Association of Official Analytical Chemists) of sanitizing for food product contact surfaces is a process which reduces the contamination level by 99.999% (5 logs) in 30 sec.
Idophor and Starsan both are FDA approved. They kill just about everything we need to worry about in food handling in less than a minute contact time, depending on the concentration.
One step is really just little more than a strong cleanser. Since it came with your kit use it up...but let everything soak initially for 5-10 minutes.
And as soon as you use it up get one of the real sanitizers. Like I said you can just dip stuff in it for 30 seconds and use it with your beer (like if suddenly your thermometer falls off the side of your pot while you are cooling your wort. You can just dip a pair of kitchen tongs into the sanitizer, cout to 30 and fish it out.)
You can also find Idophor Sanitizers in farm and feed stores...8 dollars for an entire gallon of concentrate...as opposed to 4 bucks for a little 10 ounce bottle.
Both Idophor and Starsan have their strengths and weakness...and their fans. Whichever you choose the one thing you don't have to worry about is them not doing their job.
If you really want to understand it all, you can read this geek document
http://edis.ifas.ufl.edu/FS077