Separate rooms and swapped smells come first
Set the cat up in a safe room with her tray, food, water, bed, and hiding place, and keep the dog out of it entirely. For the first days the introduction is olfactory: swap bedding between them, rub a cloth on the cat's cheeks and leave it near the dog's bed, and feed both animals on their own sides of the closed door. A dog who can eat calmly a door's width from the cat's smell, and a cat who investigates the dog's blanket and then eats beside it, are both showing you the groundwork is landing.
Assess the dog honestly during this stage. A dog who spends the day fixated on the door, whining, scratching, and unable to settle or respond to you is not ready for visual contact, and that stage needs more time and training, not optimism.
First sightings happen through a barrier, dog on a lead
Use a sturdy baby gate or a door opened a crack and secured, with the dog on a lead held by a calm adult and the cat entirely free on her side to approach, watch, or leave. Reward the dog generously for the exact behaviour you need for life together: noticing the cat, then turning back to you, sitting, and settling. Keep these sessions to a few minutes and finish while everyone is still bored rather than thrilled.
Never hold the cat in your arms for the meeting. A restrained cat who panics becomes a scratched person and a dog who has learned the cat is exciting prey-shaped commotion. The cat's freedom to leave is not a courtesy; it is the safety mechanism that keeps her behaviour quiet and readable.
Same room, with the geometry arranged for the cat
Progress to shared space only when the dog can lie settled on the lead with the cat in view and the cat chooses to remain in the room. Arrange that room for her: a high perch, a clear route to her safe room or a gate she can slip through and the dog cannot, and no corners where she can be trapped. Keep the lead on, trailing or held loosely, for the early sessions, and keep feeding, playing, and training the dog in the cat's presence so she becomes background to good things rather than the main event.
Watch for the dog behaviours that pause the plan: hard staring that the dog cannot be called out of, stalking posture, lunging, or chasing during any slip. Chasing is self-rewarding and rehearses exactly the habit you are trying to prevent, so prevent the opportunity rather than correcting afterwards. If the dog has a known history of harming small animals, or cannot settle through the barrier stage, get a qualified behaviour professional involved before any shared-space work, and discuss the setup with your veterinarian.
The long game after a good start
Keep the cat's safe room permanently available, feed the animals apart, and never leave them alone together until you have weeks of relaxed coexistence, and even then many households keep separation when out, which is a perfectly good permanent arrangement. Progress is measured in the dog ignoring the cat while she crosses the room and the cat choosing the same sofa, not in how quickly the lead came off.
Keep both animals' notes in one place
Record which stage you have reached, what the dog is being rewarded for, and any incident, however small, so a partner or family member does not freelance a faster introduction on a day you are out. KinsLe's Family Sharing lets everyone handling them work from both animals' current notes together, keeping the cat's safety rules and the dog's training stage consistent in every pair of hands.