The promotion records consist of pretty much everything that is in the soldier's military records, including decorations (medals), dates of service, dates of assignments, duty positions (past and present), performance reports, educational accomplishments, military training, official photograph, records of disciplinary action, such as Article 15, or courts-martial convictions, letters of reprimand, etc.
The members of the board discuss and score each record, and then make a determination as to whether or not the individual should be promoted (remember, the board is told in advance exactly how many in each MOS can be promoted that year).
The sucky part of this process is that if a member is not selected, the board will not tell him/her (individually) why. However, following the conclusion of the board, the President publishes a synopsis, which gives an overview of which factors (in general) the board looked at the most (which may or may not have any bearing on what is primarily looked at the next year).
The Army then takes all the selectees (without regard to MOS), and assigns them a promotion sequence number, which is assigned according to seniority. For example, if it's the E-7 list, the Army will give the lowest sequence number (0001) to the E-7 selectee with the most time-in-grade as an E-6. Each month, for the next 12 months, the Army will then release the sequence numbers of those to be promoted during that month. This ensures a smooth promotion flow for the following 12 months (when the next board will meet and do everything all over again).
Note: You've probably noted that, like corporal/specialist, the grade of E-8 is also divided into two ranks: Master Sergeant and First Sergeant. Like the specialist/corporal, Master Sergeants and First Sergeants are paid the same (both are E-8s). However, the First Sergeant has a much larger degree of authority and responsibility. The First Sergeant wears special rank (with a diamond), and is the top enlisted leader in the unit. First sergeants work directly for the unit commander and are responsible for the morale, welfare, and discipline of all of the enlisted members assigned to the unit. For more details, see Dedication to the First Sergeant and Day in the Life of a First Sergeant.
So, how long does it take to get promoted in the Army? Remember, it's dependent on the particular MOS (job) and how many vacancies (due to separations and retirements) there are in that job. On average, however, one can expect to be promoted with the following time-in-service (2001 statistics):
- Private (E-2) - 6 months
- Private First Class (E-3) - 1 year
- Specialist/Corporal (E-4) - 18 months
- Sergeant (E-5) - 4.2 years
- Staff Sergeant (E-6) - 8.5 years
- Sergeant First Class (E-7) - 13.6 years
- Master Sergeant/First Sergeant (E-8) - 17 years
- Sergeant Major (E-9) - 20.8 years