I heard that casein (protein found in cottage cheese) is only good to have at night. Should I not eat cottage cheese during the day?

All proteins are fine at all times. There is a lot of advertising and marketing hype about times when certain ones are better - and I'll agree, for example, that a slower-digesting protein is superior at night than a faster-digesting one, but more important is your intake over the entire day and not the specific timing, etc.