What does stake have to do with it?  Yet another term included in the wallet that there is no documentation of.  5 days, 10 days, 20 days....which is it?  And why?  And when does stake go up?  I have twice as many stones as in your example, have waited twice as long, and have 0 stake still.  When will this number change?  What does it do when it does change?

"So at day 6 you have 600 mint-weight and can generate less than 1 stone (will show as 0).
at day 8 you should have 800 which means you can generate 1 stone."

Well that may be how it is supposed to work but that isn't how it does work.  I have twice as many stones as that, have waited twice as long, and have not minted anything.  And my mintweight has actually now gone down from 87 to 83 in the time it took to write this.  beloweight went down again also, to 155 despite not doing anything.