from memory when I went to the nirvana upgrade on my AKSA 100 it only took a few hours including dismantling and reassembly time.
Re-biasing etc adds a bit of time, but if you already have the 100 in stock form, then you know about this.
I did it over an evening and was listening again that night...
You will notice an improvement pretty much straight away and after letting it all burn in a bit the improvements keep coming.