I have ordered a 2019 CNC ready mill, but I plan on using in the manual configuration to learn milling. The sales person is putting together a package of starter equipment for me. What are the tools and accessories that I should start getting to have in my inventory? I think that a rotary table would be extremely helpful, but that might be my inexperience.

It really Depends on what you are planning to do.....

But a Vice, Some Clamps, Stock up on Various size Endmills,

Maybe a Work holding Plate...

Oh yea ....

Plan an Enclosure for it......You will have Chips Everywhere.....