Phones can sit on the shelf for... however long, until they're sold... so first charge times vary. Just how long the charge will last depends on how much you use the phone and what you do during that time. If you charge it up fully (100%) and never even turn it on, it'll last for many, many, many days. If you use the phone, download apps, make calls, text, play games, email, browse the internet, or simply run through the settings to see what you can do, then the battery will start depleting. How much? Who can even guess at that? If you think about it, your questions can have a million different answers.