Harvesting at different moments, other not? Partial harvest, or not? What to do?

Yes, absolutely harvest individual plants when they are ready. whether you use a tent, a carboard box or some mesh racks hung in a room... controlling temp, rh and keeping it dark are the only 3 concerns. A circulation fan is good, too, but never point directly at the buds. I'm not a fan of small enclosed places while drying. Just adds risk of mold and usually causes a breeze across the bods to maintain a good RH. They can be good options once the buds have dried a few days or more... mid-60s F / 60% RH ... do your best maintaining that and it won't matter much about the rest. If you put them into a sealed container too fast, RH will spike in the container. The outside of buds will feel soft, again -- moisture evaporates off the surface of buds faster than the internal moisture being pulled to the surface. Given how i do things, i find i need about 24h beyond when the outside of buds feel dry and when i put them into containers. Simply take them out if they exhibit signs of elevated moisture in the sealed container. Repeat until buds stop exhibiting that excess moisture. There are so many variables, that it's better to understand the cause and effect rather than exact suggestions so you can adjust how you dry, when you seal up etc. A slow, cool, dark dry will do the best. might take a few experiences to get a procedure down that avoids putting wet buds into jars etc. A dust cover is fine.. but completely boxed up or in a tent is unnecessary but might be convenient. i just use and old tent frame with no canvas in a cool room. humidifier moves enough air to keep climate consistent for me.

Prob best to do a staggered harvest. Can dry in any dark cool area, I would not dry it in the tent as its hot with the lights on and the other plant. Not a fan of multiple harvests in general, especially if its the same plant, but given your situation I think its needed. Only other option I can see if let it get overripe and then that week will be for night time and the other daytime.