How to transcode HEVC footage on a mac if you don't have CC2018 yet
Install Homebrew.

Open Terminal.
Install FFMPEG with extra features by entering the following on a single line:

brew install ffmpeg --with-fdk-aac --with-ffplay --with-freetype --with-libass  --with-libvorbis --with-libvpx --with-opus --with-x26


Wait about 10 minutes for it to install.  

From the Terminal, run FFMPEG, using a line like this:

ffmpeg -i input.mov -c:v prores -profile:v 3 -c:a pcm_s16le output.mov


input.mov is the name of your HEVC file.  It can also include a full path, but spaces need to be preceded by backslashes  “\”

output.mov is an exported ProRes quicktime movie that will play in Premiere

Do process more than one file at a time:

In terminal, go to the directory where your files are.

for i in *.mov; do ffmpeg -i "$i" -c:v prores -profile:v 3 -c:a pcm_s16le "${i%.*}_out.mov"; done


Output files will appear in the same folder appended with “_out.mov”