Introducing new stray cat to my cat with limited time

I recently posted a thread about taking my cat to my families house who just brought in a stray last week. It did not have a microchip, and we cannot find the owner. They live in the country, so there aren't too many houses around that it would have came from if it is indeed a stray and not a feral (though we plan to continue looking). As of right now, I have agreed to take the cat in with my cat that I currently have as my family cannot keep any longer. I plan to keep her, as long as she gets along with my cat and we don't find an owner. The stray (or possibly feral?) cat was cleared of all diseases, but is getting spayed tomorrow, hopefully. 

Because my family can't keep her for much longer, I can't take the introductory period as slow as I would like. The cat being spayed, is further complicating things too. Some advice would be greatly appreciated. I'll try to explain how my situation has to go the next week and a half and hopefully some of you can chime in and offer some advice!

I'm visiting my family this weekend (Thursday night - Sunday morning) and have to bring my cat with me. I plan to keep the stray cat in a room while she recovers. After a few days, I was planning to start and put their food near the doors, swapping blankets, etc. However, I don't want to move too fast as the stray cat will most likely be stressed from her surgery. 

I'm also planning to leave my cat at my families house till the following weekend (7/11). That way the cats can get used to each other through the doors and what not all next week and I don't have to move the stray cat that will have just been spayed. That following weekend, I'll probably also do a face to face introduction for the first time. But then that Sunday, I'll have to put them in the car and bring them back with me to my apartment a couple hours away. Once I'm at my apartment, I can separate them again if need be. 

Both cats are very sociable with humans. They absolutely love to be around people. I adopted my cat from a local shelter. She was in a free roaming cat room with other cats, and seemed to do fine. When I walked in to the room for the first time, she came right up to me and wanted to play (she didn't seem stressed at all). The workers at the shelter said she was fine with other cats and never had issues (they have large cages for the ones that can't be with others). This makes me feel a little better about her accepting the stray cat into my home, however, I know it also depends on the other cat.

Any advice on how I should handle the next couple of weeks would be greatly appreciated! 

I would suggest that for you keep them separated.  The new stray will need time to recover and she will not be feeling her best.  She also will still have hormones coursing through her body so it would be best to just give her some time to recover.  You can do some scent swapping, but I would stop at that.

Once you are to your apt. with the cats, get a few feliway diffusers.  You will still want to keep the cats separated.  Your apt. is your cats territory and he/she will not take kindly to the newcomer right away.  Keep the new kitty in a room of her own and start intros very very slowly.  Try not to get caught up and days you should move to the next step.  Let the cats be the judge of how fast you move.  You do not want to move to the next step until there is no hissing, growling, yowling, posturing.  THis can take awhile.  When I brought a feral/stray into my home 2 years ago it was a longggggggg process.  I rushed the last steps and it backfired in my face.  It took the two one solid year to coexist.  It was daily work.  Yet I was commited to making it work.  Now they are best buddies. 

You might want to have on hand a baby gate or two (one might not be tall enough if you have a jumper), cat trees or other vertical space so the cats can get up if they are tree dwellers.  You will need 2-3 litter boxes as well.  They new kitty will need a box in her room and when the 2 are together the golden rule is one litter box per cat plus one extra.  I know it sounds like a lot, but you do not want litter box issues.

Here are some articles and a video on cat to cat intros.  Just take it slow.  The cats will be fine at your parents, but keep them separated.  It will be easier to do the intros on your turf.

http://www.thecatsite.com/a/the-ultimate-yet-simplified-guide-to-introducing-cats

http://www.catbehaviorassociates.com/a-simple-little-trick-to-use-during-new-cat-introductions/

http://www.aspca.org/pet-care/virtual-pet-behaviorist/cat-behavior/introducing-your-cat-new-cat

http://jacksongalaxy.com/2010/10/01/cat-to-cat-introductions/

Thanks for the reply.
There is a chance she won't be spayed by the weekend. if that is the case, should I forgo any introduction steps as well?

Yes, I would wait.  Get her spayed first.  If you start intros and then spay her she won't feel well for a day or so and that could cause a set back.  It's best just to wait since it won't be that long.  You can still start scent swapping and possibly you could do room swapping, but nothing face to face. 

Do you think that it is okay to share toys? Specifically wand toys? I haven't read anything really about sharing toys, mostly just sharing blankets that have their scent.

My two share wand toys with no problems, although they have different favourites/Da Bird attachments. I think sharing wand toys can actually help with the introduction process as it's another way to create positive association with each other's scent. Later on, having the one wand toy and letting the cats take turns in a joint play session can be really helpful too.

When it comes to other toys (catnip soft toys etc) my two refuse to share - no arguments...Asha simply recognises Shadow as boss, and won't touch his favourite toy (even though it started as hers! May have to get her another one of these days...).