question about horde frequency (mod with dll)

[myav]

I want to change default horde spawn interval with harmony patch.

Default spawn is 12-24h, and i want: 8-16.

Here is my code:

using System;
using HarmonyLib;
using UnityEngine;

namespace ng_HordesSpawn
{
public class ModApi : IModApi
{
public void InitMod(Mod modInstance)
{
var harmony = new Harmony("ng.hordes.spawn");
harmony.PatchAll();
}
}

[HarmonyPatch(typeof(AIWanderingHordeSpawner), "UpdateSpawn")]
public static class Patch_WanderingHorde_UpdateSpawn
{
private static int lastDayBonusApplied = -1; // protection against repeated bonuses

static void Postfix(AIWanderingHordeSpawner __instance, World _world, float _deltaTime)
{
if (__instance == null || __instance.spawner == null) return;

// === BASIC SETTINGS ===
if (__instance.spawner.numToSpawn > 0)
{
__instance.spawner.numToSpawn += 2; // always +2 zombies
}

// frequency: 8–16 h instead of 12–24
//float minDelay = 8f * 60f * 60f; // 8 h in seconds
//float maxDelay = 16f * 60f * 60f; // 16 h in seconds
float minDelay = 60f; // 1 m while test
float maxDelay = 120f; // 2 m while test
__instance.spawnDelay = UnityEngine.Random.Range(minDelay, maxDelay);

// === BONUS EVERY 50 DAYS ===
int day = GameUtils.WorldTimeToDays(_world.worldTime);
if (day <= 0) return;

int currentInterval = day / 50;
int lastInterval = lastDayBonusApplied / 50;

if (currentInterval > lastInterval) // new interval → apply bonus
{
lastDayBonusApplied = day;

__instance.spawner.numToSpawn += 1; // +1 zombie
__instance.spawnDelay = Math.Max(0f, __instance.spawnDelay - 1200f); // -20 min (1200 sec)
}
}
}
}

No errors, game accept all lines of this code.. but.... this dosen't change horde spawn frequency

Help pls with hint, what to change.