what would be you guys best guess as to how long it would take me to get it downloaded?
A large part of that is dependent on your internet connection speed and how fast your computer is. I don't think there are any specific numbers here that you can rely on.
Indexing will take the longest. The download isn't too long if you have a decent connection. It's best to download it before you go to sleep and let it index through the night (remember not to let your computer go to sleep otherwise it may not complete).
I find that the easiest way to keep a computer from going to sleep is to find a radio station that streams over the internet and let it play (that doesn't mean you must listen to it since you can mute it if you wish).
On Youtube you can find a wide variety of "10 Hours of ________" to choose from. I pick one before I go to bed, mute the video, and rest knowing my system won't shut down overnight.
(remember not to let your computer go to sleep otherwise it may not complete).
You need this from preferences (or its equivalent