if you've got your ducks in a row, you could probably get the front and rear in, in a day each... that's MY estimation on it...
rear, if you don't have driveshaft length issues, or anything go wrong, you can have done in a couple hours..
all you really have to do, is jack up the back end, pull the shock bolts, pull the u-bolts, pull the brake lines, driveshaft bolts, and ebrake cable, roll it out, roll the new one under, and rebolt up everything you took off...
for a SAS, honestly, your steering is going to be what takes the longest... depending on your spring choice, if you're going with leafs, it will be easier, and quicker, as you don't have to deal so much with alignment, and link perches, along with spring buckets... (for coils)
if you can get a steering box in and setup in short time, then i could see the whole install being done in one long day, 2 regular days... IF everything is 100% prepped...
that being said, i've not done a SAS, and that's a guess....
all you would have to do is rip everything out, and get the front axle in place, and springs welded/bolted up, in place, then the steering, you don't NEED the front driveshaft in place just yet...
you are doing a solid d35 right?