DateTime.Now only working using Date After and not Current Date

I would like to know why when I start my game the character has a Happiness and Hunger at 0. I feel like the code line PlayerPrefs.SetString("then", "01/25/2020 12:16:12"); could be the problem.

When I change the date to PlayerPrefs.SetString("then", "01/26/2020 12:16:12"); a day ahead it shows the value of Happiness and Hunger but not on the day of playing and starting the game.

I would like to start the game fresh at 100 for both happiness and Hunger. I would also want to know how I can set up System.DateTime.now a little better .

I'm following this tutorial in case anyone is lost with the way the code is set up here:

Accessing Device Time: https://tinylink.net/lX5hY

Altering Hunger and Happiness: https://tinylink.net/nV8L2

 using System.Collections;
 using System.Collections.Generic;
 using UnityEngine;
 using System;
 
 
 
 public class Robot : MonoBehaviour {
 
 [SerializeField]
 private int _hunger;
 
 [SerializeField]
 private int _happiness;
 [SerializeField]
 private string _name;
 
 private bool _serverTime;
 private int _clickCount;
 
 
 void Start() {
     PlayerPrefs.SetString("then", "01/24/2020 12:16:12");
     UpdateStatus();
     if (!PlayerPrefs.HasKey("name"))
         PlayerPrefs.SetString("name", "Robot");
     _name = PlayerPrefs.GetString("name");
 }
 
 void Update()
 {
     if (Input.GetMouseButtonUp(0))
     {
 
         Vector2 v = new Vector2(Input.mousePosition.x, Input.mousePosition.y);
         RaycastHit2D hit = Physics2D.Raycast(Camera.main.ScreenToWorldPoint(v), Vector2.zero);
 
         if (hit)
         {
 
             if(hit.transform.gameObject.tag == "Pet")
             {
                 _clickCount++;
                 if (_clickCount >= 3){
                     _clickCount = 0;
                     updateHappiness(5);
                 }
             }
         }
     }
 }
 
 void UpdateStatus()
 {
     if (!PlayerPrefs.HasKey("_hunger"))
     {
         _hunger = 100;
         PlayerPrefs.SetInt("_hunger", _hunger);
     }
     else
     {
         _hunger = PlayerPrefs.GetInt("_hunger");
 
     }
 
     if (!PlayerPrefs.HasKey("_happiness"))
     {
         _happiness = 100;
         PlayerPrefs.SetInt("_happiness", _happiness);
     }
     else
     {
         _happiness = PlayerPrefs.GetInt("_happiness");
     }
 
 
     if (!PlayerPrefs.HasKey("then"))
         PlayerPrefs.SetString("then", getStringTime());
 
     TimeSpan ts = getTimeSpan();
 
     _hunger -= (int)(ts.TotalHours * 2);
     if (_hunger < 0)
         _hunger = 0;
     _happiness -= (int)((100 - _hunger)*(ts.TotalHours / 5));
     if (_happiness < 0)
         _happiness = 0;
 
     if (_serverTime)
         updateServer();
     else
         InvokeRepeating("updateDevice", 0f, 30f);
 }
 void updateServer()
 {
 
 }
 void updateDevice()
 {
     PlayerPrefs.SetString("then", getStringTime());
 }
 
 TimeSpan getTimeSpan()
 {
     if (_serverTime)
         return new TimeSpan();
     else
         return DateTime.Now - Convert.ToDateTime(PlayerPrefs.GetString("then"));
 }
 
 string getStringTime()
 {
     DateTime now = DateTime.Now;
     return now.Month + "/" + now.Day + "/" + now.Year + " " + now.Hour + ":" + now.Minute + ":" + now.Second;
 }
 
 public int hunger
 {
     get { return _hunger; }
     set{ _hunger = value;}
 
 }
 public int happiness
 {
     get { return _happiness; }
     set { _happiness = value; }
 }
 
 public string name
 {
     get { return _name; }
     set { _name = value; }
 }
 
 public void updateHappiness(int i)
 {
     happiness += i;
     if (happiness > 100)
         happiness = 100;
 }
 
 public void saveRobot()
 {
     if (!_serverTime)
         updateDevice();
     PlayerPrefs.SetInt("_hunger", _hunger);
     PlayerPrefs.SetInt("_happiness", _happiness);
 }