Each journal stablishes its own policies, and one of them concerns to the period of time for the first review, made by the editor. You must check the Guidelines and editorial policies, or you can contact the editor to request for your manuscript. Normally, the first checking by the editor is made in the first month of submission.
You, as author have the right to ask for the process of your manuscript.
Thank you for your answer Sonia. I also know that generally within one month after submission the editor does the first-screening. In this case, almost 4 months have passed and nothing, in spite of my emails inquiring about the status of the manuscript. It looks like a quite awkward situation...