OP:
Important question:
How well is the OS running on your current HDD?
IF there are no problems other than "the slowness of the drive", you could do this, quick-n-easy:
1. Get a USB3 enclosure
2. Put the SSD in the enclosure (temporarily)
3. Connect to Mac, initialize SSD
4. Download CarbonCopyCloner. CCC is FREE to download and use for the first 30 days
5. Use CCC to clone the contents of the internal HDD to the SSD. CCC will even clone over the recovery partition.
6. Now, TEST the SSD BEFORE you install it. Reboot and hold the option key until the startup manager appears, then select the external SSD and hit return.
7. Do you get a "good boot"? Does everything look as it should?
8. If so, NOW is the time to power down and "do the swap".
When done, put the old HDD into the external enclosure to serve as a bootable backup.