First bubbles in your airlock is not a proper way to determine if your beer is done fermenting I only trust my hydrometer for that. I will let your beer be what it is, of course there are ways to stop fermentation but I will recommend you to get the basics first and then try new things. Plan your beer ahead in time (brewing software like Beersmith will help you and you can download a trial version to check if that is your cup of tea) and you´ll control your fermentables and therefore alcohol content.
I do it like this i watch airlock then when it stops i give it another week then i pop lid and peak and see if any bubbles what so ever. If no bubbles i taake a reading. Usually its right. I just dont see the point of taking so many hydro readings. If ya see a bubble in beer it isnt ready. When it looks dead like my family says then its hydro time. Thats my method and seems to work fine.
Well to each their own, I don´t take to many hydro readings, one when I think it´s done (krausen falling, etc, etc) if it is within the expected FG I wait two more days and take a second one is it´s steady it´s done simple and fool proof.
Don't try to stop fermentation to target a specific abv. At best you will have an underattenuated beer which will not taste the way you are expecting. More likely, though you will have bottle bombs exploding in your closet. There is always going to be a little variability in the brewing process. Even under the best controlled conditions +/- 0.5% abv is normal. If the abv of your beer comes out much higher than you were expecting you should revisit your process and/or recipe for the next time. In the mean time, enjoy your slightly stronger beer.
I agree with Obliviousbrew; you really shouldn't be taking gravity readings while you know fermentation is going on. Wait until you're pretty sure it's done. Each time you open your bucket or carboy you are introducing oxygen and possibly infection. Many of us who practice long-primary brewing don't take gravity readings until after 3 weeks, sometimes more, at which point if the beer is still fermenting it could be indicative of a problem.