The retreat is arranged before the doorbell
Set up the visitor plan before anyone arrives. Your kitten needs a room or a covered corner she can reach without crossing the guests' path, containing water, a litter tray and somewhere to hide, with the door arrangement allowing her to slip away unnoticed. Some kittens prefer a high perch in the same room, watching the strangers from above; either is fine provided the choice is hers. Decide which setup you will use and prepare it in advance, because improvising while a kitten is already alarmed by the doorbell produces blocked escape routes and forced introductions that set the whole project back.
Brief the visitors, not just the kitten
Guests are the variable you can actually train in advance. Ask them to enter calmly, sit down, and pretend the kitten does not exist: no reaching, no calling, no following her with their eyes, and definitely no picking her up. A guest reading a book is far more approachable to a kitten than a guest crooning at her from across the room. If she investigates, the guest should stay still, let her sniff, and drop a treat on the floor beside their shoe rather than extending a hand toward her face. Children need the same briefing in simple terms and supervision throughout, since one grabbed kitten can undo several careful visits.
Build the guest list gradually
Start with one calm adult your kitten may already have heard or smelled, keep the visit short, and end it while things are going well rather than after she has had enough. Add people one or two at a time over successive visits, and vary small details, such as where guests sit, so her confidence generalises instead of attaching to one exact scene. Normal household visiting sounds, the doorbell, coats, laughter, can be introduced in miniature outside visits too, by playing recordings quietly during play, so the real event holds fewer surprises. Throughout, protect her ordinary routine: meals, play and sleep at their usual times anchor the day even when strangers appear in it.
Know when visitors are too much for now
A kitten who hides for the entire visit but eats and plays normally afterwards is coping, and continued gentle exposure will usually help. A kitten who stops eating, trembles, hisses at familiar people after guests leave, or hides for many hours is telling you the visitor load was too large; reduce guest numbers, shorten visits, and let her stay in her retreat room with the door closed for a while. Kittens who have had little early social exposure may always prefer observing visitors to joining them, and that preference is acceptable. The goal is a kitten who is not frightened, not a kitten who performs for company.
The same briefing for every household host
Visitor plans fail when the person who opens the door forgets the plan, so write the briefing down where anyone hosting can find it: retreat location, ignore rule, treat placement, and the closed-door option. Include it in the instructions left for anyone who feeds your kitten while guests are expected. KinsLe Family Sharing keeps that visitor plan with your kitten's profile and care details, visible to the family members who help, so the briefing is delivered identically whether you are home to give it or not.