old cat and new cat issues

[deeplybaffled]

Got my long awaited kitten today.
She's about 10 weeks old and long standing baffled cat is two.
We've cat sat for a friend's persian cat before, and he and baffled cat got on fine.
I'd hoped this would be the same, but baffled cat is very unsettled.
She keeps making an odd noise, somewhere between a growl and a moan whenever the kitten comes close to the glass conservatory door between them and the kitten is backing off.
We haven't put them in the same room yet, and I'm worried about when to do so - not today, I suspect.

Has anyone else been through this? I think I was hoping that after the persian visits, this would be ok and am now wondering if this was ambitious....

We were advised to take it very very slowly. So give the kitten a 'safe' room away from baffled cat and keep it there for a few days.

Slowly introduce them by letting them share a space but let the kitten be able to escape back to it's safe room.

By slowly I mean weeks - we were told it takes a couple of months for it to all settle down

In a similar situation here with 6yr old cat and 14wk old kitten. I read it can take between two and six weeks for them to accept each other. Kitten has been here a week and the growling and snorting from big cat is subsiding. We are trying to give him lots of fuss and attention - must be hard for him with this young pretender in the house!

We introduced a six week old abandonded kitten to 16yr old fat cat.

I was a bit sad that fat old cat didn't show any mothering instinct but instead growled and spat at kitten.

We work from home so were able to keep an eye on them during the day and for the first week kept them separate at night until kitten cat has established his bed of choice (hidden under the cover at the bottom of the bed.

As kitten became more confident he started to jump around fat cat who growled and hissed but didn't go for a full on fight.

Now, a year later, they tolerate each other but the only time they've been affectionate with each other is when kitten was neutered, on coming home from the vets, he went straight to fat cat and curled up and went to sleep with her and fat cat let him.

It takes weeks to get full integration and it helps to take a staged approach:

Set new cat up in a room so they have everything they need and can settle.

Whilst old cat(s) are out the way let new cat explore to leave its scent then put it back in its room. Let old cats sniff about. There may be hissing etc. Its an invasion of territory.

Do the above a few times. When ready, open new cats door. Don't force anything. If new cat is small or worried about safety you can pop them in a dog cage or carrier to test the water.
Even the best greetings involve hissing growling etc. i advocate shorts spells and putting new cat back in room after a few minutes but repeating frequently to give respite but also give the message that they can't hiss new cat out of their territory.

Give lots of treats. Reward the slightest improvement in behaviour. Only intervene in cat disputes if they escalate to causing genuine harm or if one cat is getting upset. This can happen with kittens where the kitten keeps trying to play fight beyond the patience of an older cat.

Don't leave them unaccompanied until you're happy they're not going to hurt each other. There may well be hissing etc but only if they get in each others personal space.

It took 4 weeks for this to happen with my eldest and a new kitten but only one week for my newest edition.

A good indicator imo of how its going is whether they will eat together I.e. put a plate of treats down (but don't force yjem to do so).