The bushings that the sway bar itself ride in, fastened to the body, do not need the vehicle at ride height. There's no variability to them, the bracket the bushing sits in is to be completely tightened down. You may need the wheels at the same height so you aren't fighting the bar flexing away from the body because it has an uneven load, which could mean both wheels on the ground or both jacked up, just not one jacked up and the other not, but this is only if you don't disconnect the end links. With the end links disconnected there is no stress on the bar and it doesn't matter.
This is for ease of installation so if you can get the bolt threaded you've already got the bar close enough to tighten it all the way.
The sway bar end links, have a ball joint design rather than compressed rubber or poly bushings so it doesn't matter, except again you want wheels close enough to the same travel height so you aren't fighting different distances to install them. Whole front end up, whole front end down, either way have both sides even.
If they are polyurethane bushings, be sure to lather plenty of thick silicone grease on the inside or else they're probably going to start squeaking. Some bushings have a groove molded in to hold more grease. Some people drill a hole in the bracket and put a grease fitting on (or just leave the hole then use a grease needle) where the split is in the bushing so they can add more grease later if needed, but it might be about as much work as just taking the bolts out to regrease them again later if needed.
