SUBREDDIT: r/Pets
TITLE: Help introducing a 2yo cat to a new kitten?
POST: I'm looking to adopt a kitten so that my cat Lola has a friend to play with while I'm away at work or school and doesn't get lonely.

Lola was a former stray that I adopted from a local shelter at 1 years old, and I've now had her for a year. I don't know how her interactions are with other cats yet - the only behaviour I've seen from her regarding other animals is VERY territorial (hissing, swatting, etc) just from seeing neighbourhood cats in the backyard through the glass door. Not even making contact, just seeing one.

To me, that says that she's dominant and territorial. I'm worried she may not take a liking to another cat in her "territory", but from what I've read, an older cat has a better chance taking a liking to a kitten than another cat. I also am making an assumption that if I get a male kitten, there may not be a female-female fight for alpha cat, so they'll get along better.
TL;DR: 
Tips on how to introduce a territorial female cat to a male kitten, and best guess on how long it'll take til they can be left alone together?