Comments: How many push-ups do I have to do if I want to have a big chest? I am now starting out so doing even one push-up is a big deal for me.
I might not be an expert on this but it probably would take a couple of month or more of dedicated pushups. That includes that it should be more focused on doing it properly rather than how many! Doing an exercise wrong could practically do the opposite for you as it will damage the muscles. You will probably notice a significant amount of improvements towards your triceps and traps before anything else. Once you get past the pain of your improved abs, surely it wouldn't be much longer until your chest shows great improvements!
I agree with Sirjackz, besides you could look for apps that gradually improve your daily workout.
Personally I tend to vary the form in order to trigger differently the muscle groups.
Because you just started if you practice daily and aim high (Always careful not to hurt yourself) you could see major improvements in as little as three months.