My question would be, why do you need a time line? Your not going to a wedding or a competition right off. Take the time line off your agenda. Why put unnecessary pressure on yourself? This is for YOUR fun and health. Everyone learns at a different rate, this has been stated. At the beginning there is a TON of info to absorb. Enjoy the journey you are on.
Think about what your goals really are for dancing. Going out Fri or Sat night social dancing at the local studios or centers. Generally only Bronze level is needed, few social dancers know silver (or many silver level) patterns. Technicality is not all that important. Most of these dancers "jell" the moves/steps. (they are not crisp like competition moves)
Do you think there is any possibility you might want to take your dancing further - say doing showcases or competitions? It matters who you take with then.
As was stated earlier, going to every Tom, Dick and Harry giving lessons is way too many cooks in the kitchen and it spoils the souffle. Just because someone hangs a shingle out saying they are a dance instructor does NOT mean they are competent.
You sound like your are sorely lacking confidants. I know the feeling, I was there TWICE! (Once when I started out and later I lost it through a series of "bad events.") The last time I used Arthur Murry to help gain mine back, BUT, you will pay for their highly sugar coated boosters. AND they love their 40 min lesson plans. Get what you can from them and move on once your achieve your goal. More times than not you can get more for your money with an independent instructor. While you are absorbing what you can form A.M., research dance instructors. If you are in the U.S. - USA Dance is a good place to start. You can find social dances all over the place through them. Check out any local ballroom dance competitions in your area. Try Googling Dancesport Competitions. Buy and program and take note of the instructors and who's students are winning. What better place to get phone numbers/e-mail addresses?
When I was researching the instructor I've been with for 4 years now. I watched a lot of dance lessons and how the instructors worked. It amazed me - from over hearing an instructor telling couples taking lessons he didn't know what they were doing wrong in their dance steps, to an instructor not bothering doing patterns with his student, but she was to "get the move" with him walking in front of her the entire hour. (It was a pattern with other students in his weekly lessons.)
I watched how instructors presented their students in showcases. Apparently for some, the showcase was more about the instructor than the student/s. (one or two instructors out danced the student)
This is a fun hobby, but you do have to do a little home work to make sure your on the right path for your needs. Also you meet so many great people along the way!