You should never calibrate and then go a long period of time without recalibrating.We have a home in Cyprus, at 650 meters above sea level. If I were to analyze at home, then at sea level, there may be a difference? Haven't actually tried it yet...
I have no idea why you would calibrate at home and THEN go to altitude to test your tanks. I do a whole lot of diving at different altitudes, and I always calibrate on site before doing the dives.
Alternatively, if you are planning to go to altitude and dive immediately, you could calibrate and analyze at home and then go to the dive site. I personally do not trust my tank markings for more than a day or so. It's too easy to make a mistake. I can name several divers who trusted their memories of what was in their tanks, and their names are well known because they were wrong.