StartTmer

private void StartTimer(TimeSpan waitTime, Action onComplete, Action<TimeSpan> onUpdate)
        {
            TimeSpan second = TimeSpan.FromSeconds(1);
            TimeSpan timer = TimeSpan.Zero;
            IDisposable disposable = null;

            disposable = Observable.Timer(second)
                .Repeat()
                .Subscribe(_ =>
                {
                    timer.Add(second);

                    onUpdate?.Invoke(timer);

                    if (timer >= waitTime)
                    {
                        disposable?.Dispose();

                        onComplete?.Invoke();

                        timer = TimeSpan.Zero;
                    }
                });
        }