Help with Enemy Spawner!

Hello, I am making a game where enemies spawn after 300 seconds (5min) and in 3 second intervals (each enemy appears 3sec after each other). How would I go about writing this (Java) code? I was think about putting this code on an object so the enemies spawn from that object. Please help! Thanks.

I do not use javascript much, but here is the barebones idea:

public var enemy : GameObject;

function Start () {
	
	yield WaitForSeconds(300);
	InvokeRepeating("SpawnEnemy", 3, 3);
}

function SpawnEnemy() {
	
	//Instantiate the enemy prefab
	var enemyClone : GameObject = Instantiate(enemy, Vector3.zero, Quaternion.identity);
	//More code to make the enemy do stuff...
}