Go ahead and buy the SSD now, you won't regret it. And when you do get it, install a clean, fresh copy of Win10 on it using a Windows Media Creation Tool usb/flashdrive. Morphing the os from the old HDD over to the SSD is nothing but headaches in the long run. Just make sure that you back up all your important files such as documents, pictures, and other stuff. Better yet, before you install the SSD, disconnect the HDD from the system.