Question

How to setup service to something (api request) everyday at particular time.
I dont know.
Right now I thing about two options:
1. Setup timer and every hour check the time and if it right, do a request.
2. setup the alarm, by alarmManager, but I dont know how to do it.

Another imported thing is the request must be a little random.
About 3-10 minutes, to prevent blocking the server by too many
request at the same time.

Answer 1

Take a look at this tutorial for scheduling events with an AlarmManager.
For the interval of 3-10 minutes you could just add something like

int rand = (int) (Math.random() * 1000 * 60 * 7 + 3 * 60 * 1000);
am.set(AlarmManager.RTC_WAKEUP, cal.getTimeInMillis() + rand, sender);