Start Animation from Random Frame

class Example extends Phaser.Scene
{
    constructor ()
    {
        super();
    }

    preload ()
    {
        this.load.setBaseURL('https://cdn.phaserfiles.com/v410');
        this.load.image('bg', 'assets/skies/sky5.png')
        this.load.spritesheet('mummy', 'assets/animations/mummy37x45.png', { frameWidth: 37, frameHeight: 45 });
    }

    create ()
    {
        this.add.image(400, 300, 'bg');

        this.anims.create({
            key: 'walk',
            frames: this.anims.generateFrameNumbers('mummy'),
            frameRate: 12,
            repeat: -1
        });

        const sprite1 = this.add.sprite(50, 100, 'mummy').setScale(4);
        const sprite2 = this.add.sprite(50, 300, 'mummy').setScale(4);
        const sprite3 = this.add.sprite(50, 500, 'mummy').setScale(4);

        //  By setting randomFrame to `true` it will pick a random frame to *START* the animation from

        sprite1.play({ key: 'walk', randomFrame: true, delay: 2000, showBeforeDelay: true });
        sprite2.play({ key: 'walk', randomFrame: true, delay: 2000, showBeforeDelay: true });
        sprite3.play({ key: 'walk', randomFrame: true, delay: 2000, showBeforeDelay: true });

        this.tweens.add({
            targets: [ sprite1, sprite2, sprite3 ],
            x: 750,
            flipX: true,
            yoyo: true,
            repeat: -1,
            duration: 8000,
            delay: 2000
        });
    }
}

const config = {
    scale: { mode: Phaser.Scale.FIT },
    type: Phaser.AUTO,
    parent: 'game-container',
    width: 800,
    height: 600,
    pixelArt: true,
    scene: Example
};

const game = new Phaser.Game(config);