Wow, a lot of complicated, or should I say over complicated methods here. Since this is your first batch all you need to do is use whatever sanitizer you've got and soak them in it for the proper amount of time. For Starsan and Iodophor that is like 2 minutes and you're ready to bottle. .
Then...
You only buy once if you don't break it five minutes after buying it...which is very likely with a hydrometer. Besides that the additional accuracy isn't really needed for our needs IMHO.