You cannot its android, that's the con of using android but iphone can get locked down and tracked, but if you left up location and probably data or wifi (if he connected to unlocked one) you maybe can see where the phone is currently.
If you have gmail, you maybe can find it, if not you're doomed.
Soo basicly, login into google with your gmail account, go to google maps and in --- three lines select time line.