Judge the second week, not the first days
A cat in a foster-to-adopt trial is showing you two different animals. In the first few days she is coping with new smells, new sounds, and a new litter tray, so hiding under the bed, skipping a meal, or sleeping in strange bursts tells you almost nothing about fit. What matters is the direction of travel: is she eating more confidently each day, exploring one room further, and recovering faster after a doorbell or a dropped pan? By the second week, the pattern underneath the nerves is usually visible, and that settled pattern is the cat you would actually be adopting.
Set up one base room and keep life boring
Start her in a single quiet room with her tray, water, food, a scratching post, and a hiding spot that is hers to leave, not one you drag her from. Visit often, sit on the floor, read or work nearby, and let her choose every approach. Keep feeding times, visitor numbers, and household noise at the level your real life will have later in the trial, because a cat who only copes in an artificially silent home has not been tested against the home she would keep. Predictability is what turns watching into reliable information.
The specific things worth writing down
Keep a short daily note on the details that decide daily life together. Is she using the tray reliably, and does she prefer it covered, open, or in a particular corner? Does she eat readily, graze, or need coaxing? When does her energy peak, and is that burst at an hour you can live with? How does she respond to being stroked, picked up, and groomed, and how quickly does she forgive a startle? Note, too, how she treats other pets through a door or gate, since a trial rarely allows a full introduction safely.
Red flags versus normal trial nerves
Some struggle is expected and fades: a night of yowling, a day of poor appetite, or wariness of one household member who moves fast or speaks loudly. Pay closer attention to problems that stay flat or worsen across both weeks despite a steady routine: persistent refusal to eat, toileting away from the tray with no improvement, aggression that escalates rather than softens, or a cat who remains so distressed that she never rests in the open. Raise those with the rescue during the trial, not after it, because they may know a context that changes the picture, or a different home may suit her better.
Decide honestly, for her sake as well as yours
A trial that ends in a return is not a failure if it was run kindly and attentively; it is information the rescue can use to place her better. If she fits, confirm the adoption promptly and keep the routines that worked. Either way, pass your daily notes to whoever holds her record next, because details like her tray preference and her evening energy peak are gold for the next home. When the adoption goes ahead, KinsLe's Transferrable Profiles let her profile pass to you with her history, routines, and your trial observations kept together rather than starting from a blank page.