Fruit Ninja kind of game: Blade hitting multiple fruits...

So i have this code: when the blade hits a fruit - a Prefab with sliced pieces and some particle effects instantiates (fruit explodes). How do i make another Prefab (2x combo) instantiate when blade hits second fruit within half of a second? I know this must be easy but i am struggling.

This is the code i have:
void OnTriggerEnter2D(Collider2D collision)
{
if (collision.tag == “Blade”)
{

        Vector3 direction = (collision.transform.position - transform.position).normalized;

        Quaternion rotation = Quaternion.LookRotation(direction);

        Instantiate(fruitSlicedPrefab, transform.position, rotation);
        
        Destroy(gameObject);
    }

Create a variable to act like a timer and takeaway Time.deltaTime in Update()

float timer = 0.5;

void Update()
{
    timer -= Time.deltaTime
}

void OnTriggerEnter2D(Collider2D collision)
{
    if (collision.tag == "Blade") {
        if(timer > 0)
        {
            //combo
        }
        timer = 0.5
    }
}