AsyncTimer.cs

var i = 1;

var timer = new AsyncTimer(1000, false)
{
    Callback = async (timer, token) =>
    {
        Console.WriteLine(i++);

        if (i > 5)
        {
            await timer.StopAsync();
        }
    }
};

await timer.StartAsync();

Console.WriteLine("Hello, World!");


public class AsyncTimer
{
    public Func<AsyncTimer, CancellationToken, Task> Callback;

    private readonly int _period;

    private readonly bool _runOnStart;

    private readonly CancellationTokenSource _cancellationTokenSource;

    public AsyncTimer(int period, bool runOnStart = false)
    {
        _period = period;
        _runOnStart = runOnStart;
        _cancellationTokenSource = new CancellationTokenSource();
        Callback = (_, _) => Task.CompletedTask;
    }

    public async Task StartAsync()
    {
        var timer = new PeriodicTimer(TimeSpan.FromMilliseconds(_period));

        if (_runOnStart)
        {
            await Callback(this, _cancellationTokenSource.Token);
        }

        try
        {
            while (await timer.WaitForNextTickAsync(_cancellationTokenSource.Token))
            {
                await Callback(this, _cancellationTokenSource.Token);
            }
        }
        catch (TaskCanceledException e)
        {
            //The task canceled
        }
        catch (OperationCanceledException)
        {
            //The operation has been completed with an error before the cancellation takes effect
        }
        catch (Exception)
        {
            //The operation has been completed with an error before the cancellation takes effect
            throw;
        }
        finally
        {
            _cancellationTokenSource.Dispose();
        }
    }

    public Task StopAsync()
    {
        _cancellationTokenSource.Cancel();
        return Task.CompletedTask;
    }
}