Hardtobeme you make valid points regarding one month before the visit etc. Here are more details in the actual letter.
2. Appointments during a regular visit to a congregation: At least one month before the circuit overseer’s visit, the Congregation Service Committee should send to the circuit overseer the full name, date of birth, and date of baptism of any brother the body of elders will be recommending for appointment as an elder or a ministerial servant. The Recommendations for Appointment of Elders and Ministerial Servants (S-62) form should be used for this purpose.—See paragraph 14.
3. No earlier than a day or two before the start of the visit, perhaps when other congregation records are provided, the elders should provide the circuit overseer with background information that will help him have a complete view of the qualifications of the brother(s) being recommended for appointment. Such information would include letters of recommendation (or perhaps letters of introduction) from a previous congregation. During the meeting with the elders later in the week, the circuit overseer will discuss the Scriptural qualifications of each brother recommended. ( ks10 chap. 3 pars. 1-10) If the circuit overseer determines that the brother does not measure up to the Scriptural requirements to a reasonable degree, he will advise the elders accordingly and inform them how they can help the brother to qualify in the future.
It’s true that the CO will try to observe the brother or possibly work with him. Not so easy since dropping one meeting night during the visit. Also most brothers are working during the midweek for service arrangements.
Bottom line the CO determines Yes or No. He is the one that signs off on the WTS form going forward. Therefore his letter was read, “I have appointed…”