Most people try to be at tourist attractions after breakfast, without much rush. This can be between 08:30 and 10 in the morning. If you want to have the whole place to yourself, you better plan to get there super early. I mean at around 6am. This is especially important for open spaces such as squares, parks, famous beaches, instagrammable monuments, Times Square, you name it.
Getting out of bed early is worth it. Besides having the whole place entirely to yourself, you’ll probably get there by the golden hour. This you’ll give your pictures a magical atmosphere that no filter can compete with!