Introducing new cat (or kitten) to kitten at home

I have recently gotten myself a cute little kitten at the start of September. I might want to get a second cat/kitten to keep her company. I’ve done some research about introducing new cats and read guides and tips about it. However, all the resources I found were talking about "older" cats, or cats people have owned for a quite a while already.

Do those guidelines apply in this case as well? Since my kitten at home has only been here for 1 month, I’m wondering if I might be able to just let them sniff each other through the pet carrier, and maybe have them in separate rooms for 1-2 days and do a slow, gradual introduction like that.
All the guidelines I’ve read said that this process usually takes weeks. While i don’t have a problem with that in general, my apartment has only 2 ¹/₂ rooms, so I don’t really have a spare room I can keep closed for weeks.

Thanks for any inputs.

PS: If I end up getting a second cat, I plan to buy either a kitten, or a really young cat (1 year old or so).

Edit: To clarify why I’m even asking this question.
From my understanding, the problem with bringing home a new cat/kitten is that cats are very territorial, and your home is the resident’s cat territory.
I was thinking that since my kitten has been in my apartment for barely 1 month, she wouldn’t feel like it’s her territory that "strongly" yet, so I might be able to just slowly introduce them in 1-2 days, rather than going through a few weeks long process.