Thank you Erel.
I have to start AFTER Google services are started, on some device it takes 2 minutes. I write a DB with FCM device token, but the fm_MessageArrived is fired when the Google support is completelly started. I write the token, but the App is unable to respond in time, so the the third party(thinking the app is ready) doesn't get any answer in time. I'll introduce #StartAtBoot flag. I had same problem on other OS's but it was more tricky to solve.