Given what it takes to get to the plugs to do a comp test, I would have done it once the heads were on, and before putting all the the intake back together.

My 95 had two bad intakes, and the comp was okay on others cylinders. When I did the heads, I also cleaned off a ton of carbon. Then with the heads on, the comp was tested post-decarbon and the numbers were lower, real low on one of two. I didn't have the bandwidth to deal with the bottom half at the time, so I kept putting it back together.

I go through oil- probably a quart every 1000-1200 miles.