Start service delay after boot

Question

I have a classic android.intent.action.BOOT_COMPLETED app which activates with a service on startup. But it starts after i started to use my phone (1 or 2 min later). I want to execute it before user starts using the phone especially like screen lock. How can i minimize that period? I tried android.intent.category.HOME and android:priority="1000" but no effect. Also i have root privileges, i can use shell command or script. I would appreciate any help.