Lots of variables affect the timeline for good carbonation, not just the sugar. (For instance, how much yeast do you have still in suspension? Has the batch been in secondary for a month, or in primary for 2 weeks?) I use those drops every once in a while, and they always seem to take longer than adding corn sugar to the bottling bucket. I only use drops when I bottle straight out of a primary I have (rarely). I would say 1.5 weeks is normal. Incidentally, I use one drop for a 12 oz bottle.