How long is the application process to become a police officer or deputy sheriff?

It can easily take 3 months, or longer.
Steps might include:
1. turn in a written application
2. take a written test
3. Pass the physical skills test
4. take a medical physical
5. get a psychological evaluation
6. take a lie detector test
7. submit a completed background check packet. This is 40 pages, or more. It will ask about all your friends and family members, any known associates with a criminal background, every address you ever lived at, your education, grades, behavior in school, drug usage, bank accounts, credit cards, credit rating, complete employment history. You will need to provide copies of your SS card, birth certificate, HS/college transcripts, marriage and divorce records, child custody records, and criminal or civil action you have been a party to, driving record, social media activity, and more.
8. Go before the review board
9. Wait for an academy start date

Unfortunately, there are no shortcuts!

It depends on the number of applicants, the number background investigators, the size of the department. Anywhere from 4 to 6 months is a good guess

It totally depends on the jurisdiction. With the entry examinations, background, physical and psychological checks, expect it to take 4 to 6 months to get hired after you apply. The current rate of acceptance nationwide is about 1 out of 100 applicants. In your area it might be better or not.

I guess it would depend on where you are applying, how many applicants are being considered and how quickly an agency can get you scheduled for the post background examinations. Prior to applying in some counties, you have to take both the written (PELLETB) and physical (WSTB) tests and obtain what is called a T-Score. That T-Score could be the first hurdle that you must overcome as most agencies have a T-Score minimum. After your application is accepted you will have an in-person panel interview; some agencies have you submit to a video-recorded interview that is reviewed at a later date. After passing the oral interview, some agencies have you meet the Chief for an additional interview before progressing to the background process. Some agencies select the top candidates from the application/panel interviews and those will go to backgrounds. Once a candidate passes the background process, he/she will have to take either a polygraph or voice stress analysis test, a psychological written test and oral interview and a medical examination. Once all the examinations are completed, all of the information will either go straight to the Chief or to a review panel to select those candidates who will be hired and sent to the Police Academy. Sometimes, the actual start date for the Police Academy may not coincide with the completion date for the testing process so there may be a delay on any job offer.

All told, 4-6 months from application to offer of employment is probably about right. The Police Academy in CA is a 6-month course.

Hope this helps.