upgraded my mac mini to use and ssd and a hard drive
1 - 2 horas
wanted an ssd boot drive.
worked perfectly. make sure you sit down to do it when you are not rushed. the screws are tiny and you should be able to pay attention without being distracted.
it took me about 2-3 hrs with a break in between.
the manual probably states this, but you will need to keep the original drive in its current position. i don't believe the kit has the required tools to flip the drives. you can just reinstall the mac o/s onto the ssd. in my case, i actually had an install of Windows 2012 Server on my SSD and the Mac bios detected it and let me boot right to it.