Hello Eman,
I'll give you my experience of KC anyway although it may not be the lengthiest. I was diagnosed in April last year just before my 21st Brithday (22 now) and that is as long as I have been diagnosed with KC. I had always had what I thought was an astigmatism and nothing more in my right eye as I didn't have any problems seeing binocularly and I even passed my driving test with my dodgy right eye about 2 years before I was diagnosed.
Prior to the 3 years leading up to my diagnosis at the end of my uni degree the last time I had been anywhere near an opticians was when I was about 9-10 years old and even then that was only for a magnification prescription. No one ever told me about things like floaters so I assumed they were just part of what everyone else saw, in fact I didn't really notice the blurring around things until I was told what the effects of this condition would be last year.
For all I know then I could well have been affected by KC for a long time prior to my diagnosis, however since my diagnosis in April and contact lens fitting in June last year there has been no change in my prescription or the fit of my contact lenses. At my most recent appointment with my optometrist I asked him whether he thought there had been any change in the cone as I believed that I had noticed a change when looking at my right eye in the mirror over the past few weeks. He assured me however that there had been no change, for one thing I would probably have known about it very quickly through things such lens intolerance which I was not experiencing, he also told me that there were no stretch marks on the cornea so there had been no change as far as he or I could detect.
To sum up then, I am on my first fit and prescription of contact lenses and I have noticed no changes since I began wearing them and as far as I am aware I have only suffered from KC since my diagnosis. My hope in some respects however is that the KC did hit when I was young and I did not notice that anything was wrong due to my left eye compensating, for the moment the condition appears stable and my optometrist doesn't want to see me for another year now but has said that if I do encounter any problems to come and see him immediately.
Perhaps going nearly a decade between having my eyes checked was a bad thing but given the way I took the initial diagnosis which was not very well as it wrecked a lot of what I had been working towards it was perhaps better in some respects that I was diagnosed that bit older than I could have been.
For now though I've just got to remain positive as I've tried to do throughout this whole experience and being told that you don't have to go back to a hospital for another year given my experiences of them was even better than Lewis Hamilton winning the F1 world championship this year. (I should warn you this is a major petrol head talking here

)
All in all then I've just got to wait and see what happens, I know that it could all go belly up but at the moment my KC is in a good state and I'm not going to degrade that news as my situation could be a lot worse.
Hope you find this a bit encouraging Eman
Regards
Jez.