I turned on spawnFirstDay, that didnt work
i waited 10 days for the horde, it didnt spawn

heres the config file :
`
["Horde Event"]
#Time in ticks between spawns for the horde spawn event.
hordeSpawnInterval = 1000
#Amount of days between horde spawns
hordeSpawnDays = 10
#Amount of days a horde event can be randomly extended by
hordeSpawnVariation = 0
#Set to false to completely disable the horde event and anything relating to it.
enableHordeEvent = true
#Set to false to disable the use of beds during a horde event.
canSleepDuringHorde = false
#Multiplier by which the spawn amount increases by each time the event naturally spawns. (Set to 1 to disable scaling.)
hordeSpawnMultiplier = 1.05
#Length of a day (use only if you have another day that changes the length of the day/night cycle) Default is 24000
dayLength = 24000
#Amount of mobs to spawn per wave.
spawnAmount = 80
#Time in ticks the event lasts for
hordeSpawnDuration = 6000
#A list of entities to spawn followed by the spawn weight then the day they first appear on then the last day. Higher weight is more common. Leave the last value to 0 to set no max day, entities can have nbt attached to them.(e.g. minecraft:zombie{ActiveEffects:[{Id:12,Amplifier:0,Duration:10000}]}-20-0-0)
spawnList = ["minecraft:zombie-30-0-20", "minecraft:zombie_villager-3-0-20", "minecraft:husk-30-30-0", "minecraft:drowned{HandItems:[{id:trident,Count:1}]}-1-30-0"]
#Do the daylight cycle (and active horde events get paused while there are no players online.).
pauseEventServer = true
#Set to true to enable the horde spawning on the first day. (Game day 0)
spawnFirstDay = true
#How much should the size of each horde scale down by when multiple players are near each other?
hordeMultiplayerScaling = 0.8
#What time of day does the horde event start? eg 18000 is midnight with default day length.
hordeStartTime = 18000
#Max cap for the number of entities that can exist from the horde at once.
hordeSpawnMax = 160

[Infection]
#Whether later levels of infected should slightly slow movement speed?
infectSlowness = true
#Can villagers be infected.
infectVillagers = true
#How long do each of the 4 effect phases last for before the next phase is activated?
ticksForEffectStage = 6000
#Whether later levels of infected should depleet hunger quicker?
infectHunger = true
#Can players be infected.
infectPlayers = true
#A list of items which can cure infection when 'consumed' or used on an entity can accept nbt tags. eg.minecraft:golden_apple, minecraft:potion{Potion: "minecraft:strong_regeneration"}
cureItemList = ["minecraft:golden_apple", "minecraft:enchanted_golden_apple"]
#A list of entities that can be infected, followed by the chance out of 100 to infect, then the entity to convert them to, entities can have nbt attached to them.(e.g. minecraft:villager-85-minecraft:zombie_villager{ActiveEffects:[{Id:12,Amplifier:0,Duration:10000}]}), note: players and villagers have special code accociated with them, and should not be in this list
customConversionList = ["minecraft:horse-65-minecraft:zombie_horse"]
#Chance out of 100 for a villager to get infected
villagerInfectChance = 85
#Mobs in this list can cause the infection effect.)
infectionEntities = ["minecraft:zombie", "minecraft:zombie_villager", "minecraft:husk", "minecraft:drowned", "minecraft:zombie_horse", "hordes:zombie_player", "hordes:drowned_player"]
#Chance out of 100 for a player to get infected
playerInfectChance = 75
#Do entities on the infectionEntities list automatically target entities on the infectionConversionList
infectionEntitiesAggroConversions = true
#Set to false to completely disable mob infection and anything related to it.
enableMobInfection = true

[Misc]
#Whether skeletons and strays burn in sunlight.
skeletonsBurn = true
#Whether zombie horses burn in sunlight.
zombieHorsesBurn = true
#Whether to use zombie players as graves all the time. (Even if infection is disabled)
zombieGraves = false
#Whether to always spawn a drowned if a player dies underwater. (Even if infection or zombieGraves are disabled)
drownedGraves = false
#Whether zombie horses are aggressive or not.
aggressiveZombieHorses = true
#Whether zombie players and drowned players burn in sunlight.
zombiePlayersBurn = false
#Whether skeleton horses burn in sunlight.
skeletonHorsesBurn = true
#Whether to spawn drowned players when a player dies underwater instead of a zombie player. (Whether the zombie is spawned from infection or zombieGraves being true)
drownedPlayers = true
#Whether zombie villagers have vanilla curing mechanics or not
zombieVillagersCanBeCured = false
#Whether zombies and drowneds burn in sunlight.
zombiesBurn = true
#Whether zombie players and drowned players should be immune to fire damage
zombiePlayersFireImmune = false
#Whether unmounted horses are scared of zombies.
zombiesScareHorses = true

`

heres the client :

`
["Horde Event"]
#How do players get notified of a horde event. 0: Off, 1: Chat, 2:Action Bar, 3:Title
eventNotifyMode = 2
#Play a sound when a horde wave spawns.
hordeSpawnSound = true
#Colour of horde notification messages in the rgb format.
hordeMessageColour = [135, 0, 0]
#How long in ticks does the horde notification appear? (Only applies to modes 2 and 3)
eventNotifyDuration = 60
#Colour tint for drowned players.
drownedPlayerColour = [144, 255, 255]
#Colour tint for zombie players.
zombiePlayerColour = [121, 156, 101]

[Infection]
#Play a sound when the player beomes infected.
playerInfectSound = true

`

playing on 1.16.5 right now