advice needed on introducing cats

[qazxc]

Bella (the new cat) is currently sequestered in the kitchen, so that she can get used to the new house and have her own space. Molly (existing cat) has the run of the rest of the house.
I have brought stuff that molly has slept on into bella and stroked molly after stroking bella, to get them used to one and others scent.
I have let them catch a glimpse of one another holding kitchen door couple of inches open so that they could smell each other but not fight. there was some hissing and growling from molly, so i stopped.
Any advice on the next step?
both cats have shared before so hopefully there weren't be a fullscale war.

just keep doing what you are doing maybe leave the door open a little bit longer each time, two female adults is trickier than one of each sex as females are the bosses in any house, when i have brought a new cat into the house im one of those people who just lets the new cat out of thier carrier with all the doors of the downstairs open and let mine decide if they want to get to know the newcomer or not, and so far no major world war three feline style, all mine get on ok

first full scale meeting today.
things have gone good. molly has sussed out that bella will run off if hissed at, so is quite happy to leave her alone as she is no threat.
Bella is a bit overwhelmed and still spends most of her time in "her" room. She is also shying away from me.
Hopefully she'll get used to the new status quo soon.
how soon after moving in do you let a new cat out?

usually about two to three weeks after becoming a resident, just leave the back door open and let her decide when she is ready, and first thing in the morning before she has had breakfast so she is more likely to come back in for brekkie, and get into a habit of having a few biscuits in a small plastic box so you can rattle it to call her back in she will then associate the rattle with food and comes in handy at night too when the little sods are sitting at the end of the garden laughing at you like mine do lol

might give her another couple of weeks and try going to the garden with her. I'm a bit nervous about it as molly is an indoor cat and we live next to a busyish road. although to get her back i probably only have to open the fridge, as she usually appears demanding a treat. She's usually a very nervous and timid little thing until the fridge door opens and then she is a demanding little madam.