My annual NCOER is due in May and I will be PCSing in July. Am I supposed to complete my annual first then have a COR completed for 60 days?

You won't be eligible for a COR with only 60 days rated time. The better option is to do an extended annual taking you to the day you sign out. Otherwise, your 60 days would just be non rated time.

Your unit should do the annual. An evaluation cannot exceed 12 rated months.
There is no PCS in the reserves, but the 60 days should be captured in next year's evaluation and coded appropriately.
AR 623-3, 2-10 a (1) Normally, to be eligible for an OER or NCOER, a Soldier will complete 90 calendar days in the same position under the same rater. Nonrated periods are not included in this 90-day period (see DA Pam 623–3). For USAR TPU, DIMA, and drilling IRR Soldiers and ARNG Soldiers, the minimum rating period is 120 calendar days (see apps G and H).

Your 60 days should be rolled into next year's annual- (4) Extended evaluations reports that include any nonrated time periods since the “Thru” date of the previous OER or NCOER and prior to the establishment of a new rating relationship between the rated Soldier and the rater require the preparation of a code 10, “Extended Annual” OER or NCOER (see para 3–43a). The number of rated months will not exceed 12 (365 rated days) even though the period covered exceeds 1 calendar year. The “From” date for these OERs or NCOERs will be the day after the “Thru” date of the previously completed OER or NCOER with the rating period beginning the day the Soldier is assigned under an established rating chain (for example, the day a Soldier arrives at a new unit or the day the Soldier assumes their new duty position). The “Thru” date will be 12 rated months (365 rated days) after the arrival or assignment date while performing the same duties under the same rating officials during this rating period.

It’s 90 days bud for a COR