Introduction tips

Hi! I just got my second ragdoll cat and looking for some tips, tricks, and expectations for the introduction period.

My first cat is almost 1 year old (June 19th) (f) and my new kitten is 12 weeks (m). I thought first cat was getting lonely because she needed lots of attention and would meow non stop even when playing.

I brought our new kitten home tonight and she is very stand off. He is a very big explorer, playful, and cuddly. Almost complete opposite of her when we got her. She is typically very social and loves attention but when the new kitten is around she looks pretty upset. They have hissed a couple times at each other but for the most part trying to keep them separated. She keeps hanging out by the door because she knows he is in there. My boyfriend and I are taking turns sleeping on couch and in the bedroom with them, but wanted some tips on how to do this any more smoothly than we are. We are making she to give our first cat lots of attention, play time, treats, and not correcting hissing or swatting (she hasn’t done because she can’t get close enough) for the most part.

She typically is really social and clingy so I think she might be upset of having to share her people, but can anyone give me some expectations. I really don’t want this to go poorly. We got him so she wouldn’t be lonely.

Also how long should I expect this to continue and keep them separated.