To set financial year start month follow the steps below:

1. Go to Companies option.
2. Select the Company for which you want to set the financial year start month.
3. Click on the Edit icon from the top-right corner.
4. The edit Company window will pop-up in the center
5. Scroll down at the bottom of the window and you'll be able to check the Start Financial Year option in the Settings Menu.
6.  Select the Month and Click on Save.