JLPT Official Website
You can find the information about JLPT schedule and get sample tests.
Listening Moc Exam
There are a lot of free resources on Youtube so you can research them.
However, I put some good mock exam from Youtube for each level here.
If you know more, please let me know.
N5 Exam Listening
N4 Exam Listening
N3 Exam Listening
N2 Exam Listening