Greetings from Texas.
I use the Rokinon 14mm f2.8 with a D750 and it works pretty good for Milky Way. I haven't shot start trails yet.
You should be ok with your 18-35, just keep your shutter speed to < 30 seconds at f3.5.
I'm thinking about going to the Tokina 15-30 for a little more versatility.