Activate alarm manager 5 minutes before scheduled

I am investigating with AlarmManager and until now it is activated according to the programmed.

This is what I use

intent = new Intent(mContext, AlarmReceiver.class);
      alarm.toIntent(intent);
      sender = PendingIntent.getBroadcast(mContext, (int)alarm.getId(), intent, PendingIntent.FLAG_UPDATE_CURRENT);
      mAlarmManager.setExact(AlarmManager.RTC_WAKEUP, alarm.getDate(), sender);
      Log.i(TAG, "AlarmListAdapter.setAlarm(" + alarm.getId() + ", '" + alarm.getTitle() + "', " + alarm.getDate()+")");

I do not know if there is a way to send an Alert Dialog about 5 minutes before AlarmManager is activated.

I hope you can help me! thanks.