Angular web component (elements) input is undefined in ngOnInit

I am building a web component in Angular. My objective is to evaluate if the consumer of the web component provided a given input, in this case "accessToken". However the input is undefined in ngOnInit(), but prints in ngOnChanges()

    _accessToken;
    @Input('accessToken')
    set accessToken(accessToken: string) {
        this._accessToken = accessToken;
        console.log(accessToken); // This prints the token, but after ngOnInit??
    }

    ngOnInit() {
      console.log(this._accessToken); // Why is this undefined?
    }

    ngOnChanges(changes) {
      console.log(changes); // This prints the token??
    }

Why it's not available in the ngOnInit life-cycle hook, and how do I determine if the user provided the input or not in the most efficient way?

Any ideas are welcome