Personally I dont think you need to max out in one step.
If you want to 'save' the current tires for as long as possible, sure- maybe go to 40 and try and have them basically riding on the center of the tread...
But if you fix the alignmnet, get down to 0.01-0.02...then 36 is prolly fine.
dont worry about 'harsh on the suspension'... it is taking an absolute BEATING with everyday use. Will it feel harsher? yes. you wont really notice it in a few weeks.
oh, do you know about
www.newtis.info? They have specs there. Although BMW used to include 0.00 as 'in spec', I think it now has 0.02 front as the min (and 0,00 rear as before)
GL