How long does it take to download all blocks?
I haven't done this myself so but it will greatly depend on your connection speed. I think the entire block chain is approaching 200 GBs according to:
https://bitcoin.org/en/full-node#initial-block-downloadibdInitial Block Download(IBD)Initial block download refers to the process where nodes synchronize themselves to the network by downloading blocks that are new to them. This will happen when a node is far behind the tip of the best block chain. In the process of IBD, a node does not accept incoming transactions nor request mempool transactions.
If you are trying to set up a new node following the instructions below, you will go through the IBD process at the first run, and it may take a considerable amount of time since a new node has to download the entire block chain (which is roughly 195 gigabytes now).