This question already has an answer here:
If an academic submits a paper to a journal, it is helpful to know as fast as possible whether that journal will accept it, so that he/she can submit it to an alternative journal as fast as possible.
How long will it generally take before you know that the first-choice journal rejects your paper? Does it ever happen that the journal simply doesn't respond? (as some employers do when you send an application for a position).
I know that it is considered unethical to submit to multiple journals at once, but that does mean that the journal has a responsibility to let you know as fast as possible whether the paper is accepted or not.
(ps. I haven't published anything before)