I've heard of this trick for root beer, but dunno if it works for beer. Not a big concern for me because I keg and when I get tired of waiting on carbonation, I just crank up the CO2. Oops...the raisin trick.
With Root Beer, while filling the bottles, drop a raisin in one of them. When the raisin floats to the surface, your root beer is fully carbonated.
I have no idea if this works with beer and to be honest I have not tried it with root beer because I use plastic bottles for root beer. I know it is carbonated when the bottles get hard.
o.g. 41, f.g. 12. the ale was made from a kit, I used the 5 oz. priming sugar that came with it. The og and fg were what recipe said they would be. It may be a bit cold in my basement (63 deg.) but the last batch I bottled 3 weeks earlier carbonated fine down there.