GETH QUESTION--

I started Geth with the supplied Windows batch file.  How long does it take to download the blockchain?  How can I tell when the blockchain is completely in place?

I am assuming that the blockchain is still downloading, the console window has text streaming by.

If there is a web document with information, please point me in the right direction.  I'd like to set-up and mine ETH, but the blockchain needs to be in place.  I have been running Geth close to 18 hours now.

Any help is appreciated.       --scryptr