I second that caution about the rehydrating water being too hot. While I still see recommendations that say the water should be like 105F or thereabouts, it seems too easy for someone without a good thermometer to screw that up.
I boil my water and then cover it and let it cool to the point that it feels sort of cool. I do use a thermometer too, but I think that recommending that the water feels sort of cool is the best way to avoid disaster.
I have found that rehydrating is worth it since the batch always shows air lock activity sooner, but I also just direct pitch when I'm in a hurry. Both methods work, if you have the time, rehydrating is better. Just be sure the water is cool enough!