Well I doubt you could do it discreetly if you live with people that aren't supposed to know. If its neighbours you are worried about just be careful with evaporating solvents and anything that smells a bit dodgy. But yeah I really don't think you could get away concealing the whole procedure from people in your house/flat. (I might be wrong)
Time wise I'd say 2 days is sufficient, that been said its advisable to leave your last pull sitting in the jar for about 24hrs I usually start a tek on Friday evening and am mostly done by Sunday night, with my last pull sitting until Monday night. Evaporating can take a while, especially if you aren't using a fan. But freeze precipitating crystals is pretty quick, 8 hrs is enough to produce crystals but 14hrs in the freezer is recommended. Combine your pulls, evaporate them for around 2 hrs then freeze them all together if you want it to go quicker.
I find patience really pays off with DMT.
Best of luck!
Sonorous fractal manifestastions,
birthing golden vibrations,
that echo through folds of space & time,
ferry my soul closer to God