MonoBehaviour.didStart

Возвращает логическое значение, которое указывает, была ли вызвана команда Start.

using UnityEngine;

public class NewBehaviourScript : MonoBehaviour
{
    void Awake()
    {
        // Awake gets called before Start, therefore will print 'false'.
        Debug.Log(this.didStart);
    }

    void Start()
    {
        // Code is within Start, therefore will print 'true', as Start was called.
        Debug.Log(this.didStart);
    }
}