Hi Gabriel, I will answer each of your questions one at a time. For the first question you would say "It's already night(time) here." Saying "It's already at night(time)" doesn't make sense because saying "at" implies that what you are talking about is in a place such as "at the store" or "at the park". The difference between "early morning" and "early in the morning" is that "early morning" means around 0:00- 6:00. If you were to say "early in the morning" there is more of a personal preference and it usually starts around 5:00-6:00. For the "birds singing early in the morning" v. "birds singing in the early morning" there is no major difference. It is the same concept as your other question. So essentially "early morning" refers to 0:00-5:00. "In the early morning" v. "Early in the morning" is not really any different. "early in the morning" is more common to say though. -Camille, italki community tutor