It would be reasonably useful to run dbol for 4-6 weeks leading up to a meet. You would perform better at the meet than if you were not on it.
I wouldn't expect to retain a lot from it though long-term. There are too many factors to be able to determine how much you would retain. It really depends on how strong you are now, and how close you are to your natural limits. If you've been lifting for a year and are putting up like a 1200 total, then I bet you could keep a lot of your strength. If you're putting up an 1800 total and have been lifting for a decade or so, then your results will be more temporary.
PCT would be Nolva for 4 weeks at 20mg/day. Recovery would be relatively easy from a light cycle like this.
Most people would tell you that an oral-only cycle is dumb. My thought is that, if you're going to do oral-only, DBol is the best way to do it. Folks generally respond very favorably to DBol, and in my opinion, it's a good way to get your feet wet.