UnityException: get_time is not allowed to be called from MonoBehaviour constructor

I’m trying to make a method that prevents player from spamming Space key.

using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class PlayerControllerX : MonoBehaviour
{
    public GameObject dogPrefab;
    private float setTime = 2.0f;
    private float timer = Time.time;

    // Update is called once per frame
    void Update()
    {
        timer += Time.deltaTime;
        if (timer >= setTime)
        {
            SpawnDog();
        }
    }
    void SpawnDog()
    {
        // On spacebar press, send dog
        if (Input.GetKeyDown(KeyCode.Space))
        {
            Instantiate(dogPrefab, transform.position, dogPrefab.transform.rotation);
            timer = 0;
        }
    }

}

And this is an error statement from Unity: I think it was not a logic error

UnityException: get_time is not allowed to be called from a MonoBehaviour constructor (or instance field initializer), call it in Awake or Start instead. Called from MonoBehaviour ‘PlayerControllerX’ on game object ‘Player’.

>Solution :

Like say there you cannot set private float timer = Time.time; on the declaration.
You should do something like this

private float timer = 0;

void Start(){
timer = Time.time;
}