With anything new the scammers are out like crazy 🙂 I am getting reports from people getting the below email to their home and personal emails. It contains a .ZIP file which says it will will upgrade you to Windows 10. its actually an embedded malware and it will encrypt all of your pictures, video’s and files. If you see an email from ANYONE with a link to install Windows 10, delete it. Windows 10 is ONLY issued to your machines via Windows Update or from running this tool, and only this tool -> https://www.microsoft.com/en-us/software-download/windows10
As for the question to when you should install it, our recommendation is to wait until after 9/1. I would also HIGHLY recommend you take a full backup of your machine 1st.