Hi there I'm Dr. Sara - congratulations on your soon to be new addition!
Cats are persnickety critters and their social cues can be subtle and complicated. It's best to try to continue your routine as "normally" as possible and make sure you continue to give the same amount (or more) attention to your current cats even when the kitten is present.
It's best to keep the new cat separate from the resident cats for at least a week, just in case the new kitten is carrying anything infectious like an upper respiratory infection. During this time, your new kitten's scent will be around and your resident cats can get used to her. By keeping the new kitten in one room, the resident cats can familiarize themselves with her scent but not have to be face to face with her. After her quarantine is up in a week, you can start the formal introduction process by bringing her out of her room, whilst allowing your resident cats to go into her her room (without actually meeting her). This gives her a chance to explore her new home without being followed or frightened by your resident cats, and it allows the resident cats to get a good sniff of her environment.
It's a flexible process from there, depending on how they all interact with each other. If they seem to get along well, then introduction periods are shorter. Engaging them all in play at one time can be helpful - something like getting them all interested in a laser pointer or a special toy. This is a great ice breaker. If there's any tension, then I'd keep them separate while you're not around until you're confident everyone seems to be OK. They will need some freedom to set up their own hierarchy and social group, so unless there's signs of aggression, I try to just treat them all equal and allow them to work out their social status on their own.
Here is a link from the ASPCA about introducing new cats: https://www.aspca.org/pet-care/virtual-pet-behaviorist/cat-behavior/introducing-your-cat-new-cat
Please let me know if I can answer any other questions for you :)