You can use this link and download Windows 10 and burn it to a DVD or put it on a USB stick and then you can install it anytime that you like. It will only install on an computer with an eligible version of Windows. You can also install right from the webpage.
https://www.microsoft.com/en-us/software-download/windows10If you are uncertain about the update, you can wait or you can do a complete image backup of your current boot hard drive and can always restore that image to your computer if you don't like Win 10.
If you are moving from Win 7 you may just want to stay with Win 7. If you have Win 8 or 8.1, Win 10 is better - just be sure to go through all privacy and security settings and set them to where YOU want them and not where MS wants them.