Absolutely. A hydrometer's an absolute must if you're bottling. There are other reasons why a fermentation might have stopped: temperature drop, yeast dropping out of suspension; you don't want it starting up again in the bottle!
I never bottle before day 14 but you really need a hydrometer to work out what is going on. Recently bottled one batch after 3 weeks and even that was too early - yeast was a long and slow fermenter.