How do you know when it is time to step up and become a officer?

Bobby, different for everyone. And then, there's different motivations. Some do it for ego, money, or seeing a bigger picture. Some have done it just to get a different assignment such as getting off a medic. Those types are the ones I never wanted to follow in any capacity.
Some have done it, and I presume you're asking in a noble way, in order to fill a need for themselves to give back, and perhaps achieve in their lives. Others have realized that they had a particular level of talent and knowledge, and wished to offer to expand that beyond themselves in order to better the crew, the department, and the community.
What many fail to realize is that when you become a front-seater, you are the responsible one for all that ride that particular piece on that call, and, you are responsible for the well-being of the occupants or victims of the call you are responding to. I have heard comments of "Oh, I'LL BE IN CHARGE TONIGHT!" and I tell them "yep, you go to it" for anyone who REALLY knows what that seat entails may be a bit reluctant to take that on. Think about it, one of 'those' jumps up front and rolls up first arriving on a 2 story SFD with Mrs. Smith and the little Smith hanging out the upstairs window. Whatever happens, good, or bad, now rests directly on that person's shoulders. No excuses, no 'do-overs'.
When you wish to be the person that intervenes on that call, that's when it's time to step up and take that test, or put your name in for promotion.
If it's something you think you want to do, go to your academy and take a Fire Officer 1 class before you throw your hat into the ring. It will give you some things to think about.
Oh, and by the way, my experience: I took the test just to be taking it and to get a feel for how it went. I figured I'd probably be better ready for the next one a few years later... well, I passed the written and assessment center... and wound up 3rd... they were promoting 3... It took a case of beer with a long talk with my Dad about what I should do... his sage advice "You'll make a lot of mistakes, but remember, those Firefighters on your watch come first. You are the first in, and last out. You just remember to get them home, and you'll do fine."
Be Safe Bobby

Hey Bobby,

I can't add much more than what our good Brother Gallagher has already said, but I might add that for me, the step up came because I new I could do better than some of the people applying, and I firmly believe in leadership from the bottom up. In some departments, the only way to achieve what you believe in is to become an officer and begin to live it for the people below you. In such places, the promotion isn't always the easiest life.

Some departments are suffering from extreme shortages of leadership and as nice as it is to just enjoy the jumpseat or driving the red rig, someone has to step up.

Good Morning Brother's and sister's I am looking for some imput on different department accountability on emergency scenes.
My department has no accountability system. We are a career department of approx 88 fire fighters. Our current if you want to call it an accountability is a role call list that the Assistent fire chief carries in his car. We have no written policy on accountability. To me this is a safety issue. Any information, suggestions would be apprieciated

scott, our sops will be overhauled and out in oct, they will feature a 2 level accountability system. The first level will be tags on passports for each apparatus. The second level will be a t card system much like what is used in the wildland scene out west.