That is not necessary. iPhone batteries wear more like care tires. They wear out with use, not when you decide to charge it. You can charge it anytime it is convenient for you. It will not effect overall lifetime of the battery. Every month or so it is even recommended to let the battery go to zero which automatically shuts-off the iPhone, then completely charge it back up to 100%. Enjoy your iPhone. But the less you actually use your iPhone the longer the battery will last.