Jessie or stretch for server

[Dan <ganchya@gmail.com>]

Hi,

I'm going to install Debian on a file server (NFS and postgres) for a
small group of people. It will be in an intranet, no direct connection
to Internet.

Should I install Jessie or Stretch? I've always used stable. My
understanding is that at this point Stretch is quite stable, the
versions of the packages won't change and there won't be major changes
in the packages, only security/bug updates.

In a few months the Stretch Debian installation will automatically
become "stable". Is that correct?

If I install Jessie I'll have to update very soon.

Thanks,
Daniel