Uh... I`ll try to explain. This (the fact that some later packages arrive before those sent first) happens, because shipping logistics are not a straight line. It is not like all the packages line-up in a neat order and move henceforth in order of arrival at the first destribution center. No. Shipping logistics are complex on a normal day, and they get even more complex with holiday rush and other complicating circumstances, like Covid restrictions, which pop-up everywhere these days.
For example: Janeway gets shipped, goes to the distribution center, than another, and another, and there she sits waiting in line for a flight (most postal shipments go into cargo compartments of the regular, passenger flights). She waits in her stack of other packages, but it is holiday season, so a lot more packages arrives, more than the destribution center can accomodate, but they can`t turn those down, so they accept and stuff their storages to the top, untill they can fit no more. The order of arrival gets lost, newer packages end up on top of the older ones. Finally, the destribution center says "we can`t physically fit any more!" and the shipping company has to arrange another spaces to store the packages, that keep arriving. They open some temporary destributions centers in other areas and rerout all new packages where. At this point (two weeks later), EMH gets shipped and goes to one of the newly arranged distribution centers, while Janeway keeps lying in her overflown one. At this point, Covid is discover among the workers of the first disctribution center and it gets shut down for two weeks to test every worker and for the general quarantine reasons. So the shipping company gives flight spaces to the packages of one of the temporary destribution centers, instead. EMH gets shipped out of the country, while Janeway area is quarantined, her DC isn`t working and also she got buried under newer packages.
Now imagine that this can (and often DOES) happen in both the country of origin and the country of destination. And in any country in-between, because international shipments rarely go directly from one country to another. Add here, that not only destribution facilities, but also Customs in both countries. Which have offices with workers, who can also get Covid and be put on pause.
Here is how you can have one package arrive before another, though it had been shipped 3 weeks ahead.