I've started to use a touch of dry sparkling wine yeast (champagne yeast, EC-1118) in the bottling bucket when adding the sugar water to prime. Every batch I've done this with I've had full carbonation in two weeks. It's not really that big of a deal because without it I would get full carbonation in three weeks.
But, other advantages are that champagne yeast work in a huge range of temperatures, it's completely neutral flavored and drops like a stone once the bottles are in the fridge. Thus, I've started to cold crash the native yeast out of my beer when I use the champagne yeast. Maybe more of a PITA than it's worth for some people but I've enjoyed the results. Also no need to worry about high alcohol beers or beers that have been sitting in a carboy for a really long time using this method as you've got fresh troops ready to tackle the sugar.