As far as I know, the 1 year time commitment is for actual time worked in the handler position, so no leave time would count. I tried this route too being a former handler. I asked if previous time worked would count towards the 1 year requirement, and was told no. So with the clock reset, I became a handler a 2nd time, but then left before the year when I got a full-time flying job elsewhere.

Going the internal route can work as others here on this board have done it. Good luck!