I want to refactor my loading game script

Question

I wanted to load my save files in Start() but I got an error that there is no path to load file because the path is created in Start() so I changed loading place to Update() and I wanna ask is there a better and more optimal option than what I used?

using UnityEngine;

public class FirstToLoad : MonoBehaviour
{
    public SaveLoad saveLoad;
    public LoadScene loadScene;

    public bool isGameLoaded;

    // Start is called before the first frame update
    void Start()
    {
        StartCoroutine(loadScene.Load_End());
    }

    void Update()
    {
        if(!isGameLoaded){
            saveLoad.Load();
            isGameLoaded = true;
        }
    }
}

If someone needs to know how my SaveLoad script looks

using UnityEngine;
using System.IO;

public class SaveLoad : MonoBehaviour
{
    private string jsonSavePath;
    DataToSave gameData;
    DataManager moreGameData;

    void Start(){
        jsonSavePath = Application.persistentDataPath + "/PlayerStats.json";
        moreGameData = GetComponent<DataManager> ();
        gameData = GetComponent<DataToSave> ();
    }
    
    public void Save(){
        //Creating file or opening file
        FileStream File1 = new FileStream(jsonSavePath, FileMode.OpenOrCreate);

        //Data to save    
        moreGameData.SaveGame();

        //!Saving data
        string jsonData = JsonUtility.ToJson(gameData, true); 

        File1.Close();
        File.WriteAllText(jsonSavePath, jsonData);
    }

    public void Load(){
        string json = ReadFromFile("PlayerStats.json");
        JsonUtility.FromJsonOverwrite(json, gameData);
        moreGameData.LoadGame();
    }

    private string ReadFromFile(string FileName){
        using(StreamReader Reader = new StreamReader(jsonSavePath)){
            string json = Reader.ReadToEnd();
            return json;
        }
    }
}

Answer 1

Return the code to start() like before and instead update() use executing the code in Edit >> Project Setting >> Script Execution Order:

Answer 2

You can use the Awake() function: https://docs.unity3d.com/ScriptReference/MonoBehaviour.Awake.html

This method is always called before Start.

To use it you can rename your Start function in SaveLoad to Awake. Then you can use your function from Update in Start in your FirstToLoad class