Relatively Simple Valve Adjustment Questions

Hi everybody!

I am planning to have a DIY oil change tomorrow, and since im at it, I plan to have the valves adjusted as well. I dont think the car badly needs the adjustment but hey, with these cars, a little more precise adjustment will help!

My questions are:

1. Do I adjust it before or after the oil change? Ive read that changing oil might loosen up some engine crud and that loss of compression can occur... I wonder what the adjustments could bring.

2. What 'clearance' setting should I use? I mean, the ambient temperature at the garage is probably at 30 degrees Celsius... Should I use the 'cold' or 'hot' clearance as I intend to do the adjustments after letting the engine cool down?

Car is '76 123 200D (driven rather hard, too...)

Thank you all very much!

-DON