You can use this example basically you need to calculate the delay by notificationTime-currentTime
https://www.tutorialspoint.com/how-to-set-an-android-notification-to-a-specific-date-in-the-future
private void scheduleNotification (Notification notification , long delay)
{
Intent notificationIntent = new Intent( this, MyNotificationPublisher.class);
notificationIntent.putExtra(MyNotificationPublisher. NOTIFICATION_ID , 1 );
notificationIntent.putExtra(MyNotificationPublisher. NOTIFICATION , notification);
PendingIntent pendingIntent = PendingIntent. getBroadcast ( this, 0, notificationIntent, PendingIntent. FLAG_UPDATE_CURRENT);
AlarmManager alarmManager = (AlarmManager) getSystemService(Context. ALARM_SERVICE);
assert alarmManager != null;
alarmManager.set(AlarmManager. ELAPSED_REALTIME_WAKEUP , delay , pendingIntent) ;
}
if you need the repeat notifications at specific time interval then you can use Alarm Manager https://developer.android.com/reference/android/app/AlarmManager