Form1.cs

using Reactive.Bindings;
using Reactive.Bindings.Binding;
using Reactive.Bindings.Extensions;
using System;
using System.Data;
using System.Linq;
using System.Reactive.Disposables;
using System.Reactive.Linq;
using System.Windows.Forms;

namespace WindowsFormsApp7
{
    public partial class Form1 : Form
    {
        private CompositeDisposable Disposables { get; } = new CompositeDisposable();
        private Form1ViewModel ViewModel { get; }
        public Form1()
        {
            InitializeComponent();
            ViewModel = new Form1ViewModel();
            FormClosed += (_, __) => Disposables.Dispose();

            ViewModel.Name.BindTo(
                textBox1,
                x => x.Text,
                BindingMode.TwoWay,
                targetUpdateTrigger: Observable.FromEventPattern(h => textBox1.TextChanged += h, h => textBox1.TextChanged -= h).ToUnit())
                .AddTo(Disposables);

            ViewModel.UpperCase.BindTo(
                label1,
                x => x.Text)
                .AddTo(Disposables);
        }
    }

    public class Form1ViewModel
    {
        public ReactiveProperty<string> Name { get; }
        public ReadOnlyReactiveProperty<string> UpperCase { get; }

        public Form1ViewModel()
        {
            Name = new ReactiveProperty<string>("");
            UpperCase = Name.Select(x => x.ToUpper())
                .Delay(TimeSpan.FromSeconds(3))
                .ObserveOnUIDispatcher()
                .ToReadOnlyReactiveProperty();
        }
    }
}