1. Create a new page (with any title, it does not matter)
2. In right column go to Page Attributes > Template and select (VioMag) Magazine Front Page
3. Click on Publish
4. Go to Appearance > Customize > General settings > Static Front Page
5. Select A static page
6. In Front Page, select the page that you created in the step 1
7. Save changes
If the image thumbnails are not displayed correctly (because BMag Pro is not the first theme used) you will need to regenerate the thumbnails with a free plugin as Regenerate Thumbnails.