In Legends of Metru Nui we see the backstory of the Turaga, but we see them transform into Toa and at the end into Turaga, there was also 3 film and books inbetween. But for how long were Toa Metru Toa during their life?
Looking at BS01.com's timeline, it appears to be less than a year. I'd say about 5 months at most..
So I thought it was around or less than year, well, they had a job to do, they've done it.
Pretty much. here's BS01's timeline if you haven't seen it.
Okay, so that begs the question if they were to a for only 5 months, then why do they act so wise and as if they have years of experience. Did transforming into turaga make them wise all of a sudden?
Dunno. That always confused me too.
Well, they did lead the Matoran villages on Mata Nui for a thousand years after transforming into Turaga...
Exactly. By the time you meet the Turaga, 1000 years have gone by since their change. They have had to be leaders of their villages over all that time, so some wisdom and maturity has to come with that.