»How long did it all take ?«

I was wondering how long it took from Neo's first contact with Morpheus till the last scene of Revolutions

Are we talking days, weeks, months, or maybe years?
I have no idea, is it mentioned somewhere in the movie?

It's about 2 years.

On what facts did you base your answer?
Or is it just a guess?

that from the end of "The Matrix" to the start of Reloaded was a 6 month time period.

There's a time given at the beginning and the end of M1, about 1.5 years. Then M2 and M3 are about 6 months after that and last for a couple days.