I've done it twice, so can give you a few helpful hints. I'm sure other people will come up with more advice too.
First introduction - make sure there's at least 2 people around, one to supervise Darcey and remove her if necessary and one to do the same for the puppy. If they want to play then let them but not to the point where one or both gets over excited or the puppy becomes tired or the play becomes too rough. If Darcey is afraid or grumpy don't tell her off, but give them some time apart. They may take to each other straightaway but it could take days or even weeks.
Make sure Darcey has places where she can get away from the puppy if that's what she needs. William didn't take to Louis at all and his getaways were the sofa (until Louis got big enough to jump up) and upstairs.
The puppy will need safe places too. Sounds like you've got that organised already with his crate.
Feeding - I fed them seperately at first, Louis in his playpen, William nearby and within sight of each other so they could get used to being fed near each other. I always gave William a small treat when Louis was having his extra meals. This has never been an issue with them and from fairly early on I was able to feed them both in the same room.
Chews - William isn't a guarder but I didn't take any chances when Louis first arrived and made sure that chews were never left laying around. I don't leave dogs with chews if I'm out or at night anyway, so they only have them when I'm with them. Louis can be a bit of a guarder of high value chews and raw bones now but wasn't when he was a puppy.
Walking - Before Louis was allowed out I shut him in his pen while I walked William twice a day. I took Louis to places where I could carry him round to help his socialization. Once Louis was vaccinated I took him and William for a short walk together every morning, then William for a long walk on his own later in the day and Louis for a short walk on his own.
Barking - unfortunately William, who rarely barked, now likes to join in when Louis barks at the doorbell, fireworks etc
. I haven't yet found a solution.
My top tip is make sure that Darcey still gets some special time with you, especially if she feels put out or worried by the new arrival.
My other top tip is make sure that the puppy has some time, training and activities away from Darcey so he doesn't become too dependent on her.
Hope it all goes well