I am an infantry soldier in a non infantry unit. Do i wear the blue disc on my class A collar?

The answer is no. Same with the cord, you cannot wear either until you're back in an infantry unit. What kind of unit are you in, Cav? I've heard some 11b's get sent to Cav units.

Not unless the following applies:

(4) By whom worn.
(a) Officers and enlisted personnel of the infantry, holding an infantry PMOS or specialty, who have been awarded the Combat Infantryman badge, the Expert Infantry badge, or who have successfully completed the basic unit phase of an Army training program or equivalent.
(b) Enlisted personnel who have completed one station unit training (OSUT) resulting in the award of an infantry PMOS.
(c) Infantry officers who have graduated from the resident infantry officer basic or advanced course.
(d) Infantry officers who have graduated from the Infantry Officer Candidate Course (during mobilization).
(e) Infantry officers and enlisted personnel in the Reserve components who hold an infantry PMOS or specialty.
(5) When worn. Infantry personnel (as described above) may wear the infantry cord as follows.
(a) During the period of assignment to an infantry regiment, brigade, separate infantry battalion, infantry company (including the headquarters and headquarters company of an infantry division), infantry platoon, or infantry TDA unit. In addition, infantrymen assigned to infantry sections or squads within units other than infantry units may wear the cord when authorized by battalion or higher-level commanders.
(b) During the period assigned for duty as an Army recruiter or advisor, ROTC instructor, or member of the staff and faculty of the U.S. Military Academy, as long as personnel retain their infantry PMOS.
(c) During the period of assignment at brigade- or lower-level BT or AIT units, or in OSUT infantry units, as long as personnel retain their infantry PMOS.
(d) Infantry OSUT and IOBC graduates may wear the cord en route to their initial follow-on infantry assignment.
(e) Soldiers en route from an assignment where wear of the shoulder cord was authorized are permitted to wear the shoulder cord if they are pending reassignment to another organization authorized wear of the cord, or when assigned to a separation point for discharge purposes.
b. Insignia disk; branch and U.S. insignia.
(1) Description. A plastic disk in infantry blue, 1–1/14 inches in diameter.
(2) Approval authority. The same as in paragraph a(2), above. The insignia is issued without cost to enlisted
personnel.
(3) How worn. The blue infantry disk is worn secured beneath the branch and U.S. insignia disks, with a 1⁄8-inch
border around the insignia. infantry personnel wear the insignia on the Army green, blue, and white uniforms (see fig
28–173).
(4) By whom worn.
(a) Enlisted infantry personnel, who hold an infantry PMOS; who were awarded the Combat Infantryman badge or 263 AR 670–1 • 3 February 2005 the Expert Infantry badge, or who have successfully completed the basic unit phase of an Army training program, or the equivalent.
(b) Enlisted personnel who completed one station unit training (OSUT) and were awarded an infantry PMOS.
(c) Enlisted personnel of the Reserve components holding an infantry PMOS.
(5) When worn. The same as in paragraph a(5), above.

Replace cord with disc above and it gives the answer.

This is how I understand it... If you are in a non-infantry unit but you are in an infantry squad or section, as long as it is authorized from the BN/SQDN Commander then you are allowed to wear it.