Hi and welcome, Hungariangirl
I read all 42 pages when I found this site because I had been researching myself. Many people on here have used inman with great results.
I just had a consult last week and the ortho said most cases happen by 16 weeks, he guessed about 8-10 for me. It depends how fast your teeth move, some people noticed movement within a few days, other people didn't notice any for two weeks.
Most people said that it was hard to talk (and be understood) with an upper inman, so some users didn't wear it at work if they had to speak clearly all day (teachers, phone customer service etc). I didn't notice the same problem with lowers, although there does seem to be an adjustment period either way.
Wear time - the ortho I saw basically said 'the more you wear it, the faster your treatment will go' and based on user response here, I think the average was between 16-22 hours a day. Most people were around 18-22 with the dentist recommended to be 20 - at least that's what I saw most often.
Hope I answered your questions, feel free to ask more!