How to make it so each enemy is given a random time difference?

My game variables

#Game rules
time = 1
time_passed = 0
complete_time = 400
enemy_timer = random.choice([1000,2000,3000])
finished_enemy = pygame.time.get_ticks()
enemies_alive = 0

My creation of enemies

#creating enemies 
    if time_passed < complete_time :
        if pygame.time.get_ticks() - finished_enemy > enemy_timer:
            r = random.randint(0, len(enemy_types) - 1)
            enemy = Enemy(enemy_health[r],enemy_animations[r], WINDOW_WIDTH - -10, WINDOW_HEIGHT - 260, 2) #gets arguments from enemy class and where they are(location)
            enemy_1 = Enemy(enemy_health[r],enemy_animations[r], WINDOW_WIDTH - -10, WINDOW_HEIGHT - 160, 1)
            enemy_2 = Enemy(enemy_health[r],enemy_animations[r], WINDOW_WIDTH - -10, WINDOW_HEIGHT - 60, 3)
            enemy_group.add(enemy,enemy_1,enemy_2)
            finished_enemy = pygame.time.get_ticks()
            #allows for increasing difficulty
            time_passed += enemy_health[r]
            print(time_passed)

Sorry for wording of the question as i dont know how to describe what i want in a sentence.

Anyway I have the code for randomizing three values for enemy_timer (1000,2000,3000) what it does is separate the images of my enemy by millisecond. I want it to affect enemy, enemy_1 and enemy_2 differently. Such as when i run enemy has 1000 enemy_2 has 3000 so on.