I would suggest either ngOnInit, ngAfterContentInit or ngAfterViewInit, again depending on what you want to achieve. Example with onInit:
import {Component, OnInit} from 'angular2/core';
@Component({
selector: 'my-component',
template: '<p>{{ message.text }} </p> <p> {{ message.num }} </p>'
})
class MyComponent implements OnInit {
ngOnInit() {
this.message = {
text: 'Hello there!',
num: 4
};
}
}