Unzip these blocks in the corresponding datadir (default ~/.bitcoinzero). Then initialize your Bitcoin Zero node with zcashd -reindex option.
Main net genesis block. Default path ~/.bitcoinzero/blocks. If error occurs or being killed because of lacking memory during the initializing reindex, please try blocks_for_low_memory.tar.gz.
Test net genesis block. Default path ~/.bitcoinzero/testnet3/blocks.
Main net genesis block including index and a rev00000.dat file. Default path ~/.bitcoinzero/. Use this on a low memory machine. However, as stated on https://github.com/zcash/zcash/wiki/1.0-User-Guide, 3 GB of free RAM is needed after all.
Since Github has a bandwidth limit on downloading, this alternative is provided. BCZ_genesis.torrent contains and only contains blocks_for_low_memory.tar.gz.