Player Prefs not setting the position at start of the game

Hi I have a main menu where I delete my player prefs, and then at my level 1 I set up the player position by getting the float and writing it in the start function.

     Vector3 newPos = new Vector3(PlayerPrefs.GetFloat("PlayerX"), PlayerPrefs.GetFloat("PlayerY"), PlayerPrefs.GetFloat("PlayerZ"));
     player.gameObject.transform.position = newPos;

the script which save the positions to player prefs is as follows which I wrote at other script in the start functio:

     GameMaster.gm.spawnPoint.position = checkpoints[value].transform.position;
     PlayerPrefs.SetFloat("PlayerX", GameMaster.gm.spawnPoint.position.x);
     PlayerPrefs.SetFloat("PlayerY", GameMaster.gm.spawnPoint.position.y);
     PlayerPrefs.SetFloat("PlayerZ", GameMaster.gm.spawnPoint.position.z);
     PlayerPrefs.Save();

the problem is when I came from main menu which deletes the player prefs and I load level 1, the player's position is set up at 0,0,0 axis. I think the problem here is the player prefs not setting up at the start function, I tried writing it at the update, but the player's position will be stuck because it is called once per frame. Any help would be highly appreciated! Thank in advance