True for all new cameras which don't enjoy released support for raw files yet:
If latest release (or release candidate) of Adobe DNG Converter supports your camera, convert raws to DNG then import, otherwise you have to process the jpegs for now, or convert raws to tiff using manufacturers software and process those for now.
The only way to make sure Lightroom does or will support a specific camera model is to check, and if not supported, wait for next release, then re-check.
Sounds like a lot more work. Thanks for reply.
Here is the contents of a batch file which will convert whatever raws you drop on it:
"C:\Program Files (x86)\Adobe\Adobe DNG Converter" -cr7.1 -dng1.4 -p0 %*
Once you download the latest converter (release candidate from adobe labs, if necessary), and save the appropriate contents of the batch file (change path to match your system, and parameters to match your druthers, if applicable), the procedure is:
1. Drop raw files on bat file.
2. Import as usual (the DNGs).
Not too bad once you're set up (if DNG converter supports your raws).
Note: on Mac, you may need to use "$@" (with the double-quotes) instead of %* (which is dos batch syntax), and you will need to use the full path to the converter executable file, e.g.
“/Applications/Adobe DNG Converter.app/Contents/MacOS/Adobe DNG Converter”
If too much, just use the GUI instead of the bat file.
Native Lightroom support for the D750 was added in the Lightroom 5.7 update released this evening.