Just so there is understanding the 12 month clock starts when you terminate employment with the current employer holding the NCA. Your #3 message about "even I am still employed" -- not legal to hire you if you haven't been gone that 12 months but legal to have a contract that they will. But honestly I have to agree with PayrolGuy that it would be an unusual agreement/contract but could see it if you were unique/needed, etc and it was the only way to get you to their company.

Wording is going to be crucial and you need to also think about what happens if YOU can't fulfill the contract on time? Or that you find a different employer in the meantime for those 12 months who might also ask you to sign a noncompete. I'd also be careful of anything that could look like work or payment for or during those 12 months. This is not a DIY project.