I wouldn't even bother taking a hydrometer sample tonight. It is premature and you only run the increased risk of contaminating your batch. Even if the primary phase of fermentation has completed, which it may have, the conditioning phase has just begun. During the conditioning phase, the yeast clean up after themselves by mellowing some of the compounds produced during primary fermentation. These compounds, if allowed to remain, can lead to all sorts of off flavors. During the conditioning phase the yeast will slowly continue to convert any remaining fermentable sugars and then settle out, taking with them some of the proteins that are responsible for creating hazy beer.
Just be patient. If you intend to secondary, give it the full 7-10 days in the primary, take a hydrometer reading and rack it to the secondary for a minimum of 2 weeks, then bottle. If you are not going to secondary, then leave it in the primary for 2-3 weeks total and then bottle it. This extra time allowed for conditioning will make all the difference in the world in the quality of your beers.
John