Dear Sir,
I am a Android Developer with experience in lots of languages including Java,PHP,MySQL which I believe is needed in this project plus in lot more other languages like C,C++,C#,JS,HTML,CSS.
I already have an app which Phone Locator app which deals with Sign in,Sign up and some gps functions. So I believe taking this app as a sketch I can do your project.
I am looking forward to discuss with you about the project so that I can know what requirements you need and depending on that i can tell you the exact time and other things that you want to know.
Looking forward to hear from you soon.
Thank you!