Hey there, I am used to seeing you on WISH!
You can make it work. Get there 30 minutes before opening, and be prepared that the parking garage can be a nightmare to get into first thing. So allow plenty of time for that. Then get to the gate of DL 30 minutes before opening.
I would say do Space Mountain for sure! Its totally different than WDW's version, recently updated and a very cool ride. Far better than WDW's. The Nemo subs are up and running and your dd would love those. No fastpass. So I would actually ride that first thing, then get a fp for Space Mountain and then head over to Fantasyland and do anything over there that appeals. There are quite a few rides that they don't have in WDW's Fantasyland. Then ride Space on your fp. From there I would fp Indiana Jones (if your dd likes Dinosaur, this is the same type of vehicle and ride experience). I would get to DCA around lunchtime, that's when the crowds at DL are starting to gear up. And know that you can hold fastpasses at DCA and DL at the same time, they aren't hooked up. So before you leave DL to go over to DCA, make sure you get a fp for something so when you go back you will have that. DL and DCA both take fp's that are past the return time. They just won't take them before the return time, which is the way it is WDW for that matter.
Make sure you see Aladdin at DCA, its a wonderful show your dd will love. And that can give you a nice break to rest.
I also noticed on the DL calendar that the Electrical Parade is at 8:45 and that Remember Dreams Come True fireworks are at 9:25. Its really hard to see both of those shows the same night. I love the Electrical Parade but have to say if you can only see one of the nighttime shows, I would pick Remember. Get a good spot in the hub area about 30-45 minutes before the show and see it. Its so much more detailed than Wishes, it will start out the same but then branch off into something very different. There are some people that see the EP and Remember on the same night but its hectic and requires fast feet and some planning. Maybe one of those posters will tell you how to do that!
Disneyland on a Saturday is always going to be very crowded. Especially if its a nice day, the locals all arrive in droves. But I think you can get quite a bit done, just enjoy your day and whatever you get done is great, and anything you miss will be there for another trip!
Here is what I would encourage you to do:
Disneyland:
Finding Nemo Submarine Voyage
Indiana Jones ride
Pirates of the Caribbean, different and longer than the MK version
Space Mountain
Alice In Wonderland, Mr. Toad's Wild Ride, Storybookland Canal Boats, Pinochio's Daring Journey and Matterhorn (all in Fantasyland, all not at WDW)
Walt Disney Parade of Dreams. If you like parades I think this is a good one, my dd loves this more than the one at MK and its not at all the same.
At DCA:
Aladdin Show
California Screamin (if your dd will ride that type of rollercoaster that is!)
Grizzly River Run (if you have slickers and like Kali River Rapids, this one is actually a bit longer with two drops and very fun. But you get drenched).
Monsters Inc. Ride
Also know that the Grizzly River Run fastpass machine is not hooked to any others. So you can get a fp for that and California Screamin at the same time.
I hope you and your dd have a wonderful time this Saturday!
Edited to add: Hydroguy is right about the Magic Mornings thing. Which means by the time you enter the park, Nemo will have a very long line most likely since it is open for Magic Mornings and still very new and popular. So I would grab a fp for something else first, then think about if you really want to wait for Nemo. The line starts early and pretty much stays that way. You can sometimes find a shorter line late, late at night. So you could always do that last thing. Its a cute ride, but in my opinion, not worth a huge long wait of longer than say 45 minutes. And to be frank, its not that much different than the little Nemo ride at Epcot in my book. Longer and you are in a sub but it uses some of the same type tecnology. But again, if you want to ride it, by all means do. Just make sure you get a fp before you do for something else so that at least you have done that before you get in line.
I'll also agree that 8 -12 could be tiring but I think with some time midday to see the Aladdin Show, maybe ride the train around DL and literally let your dd doze (I have done that with my kids!) and maybe even go to DTD to see a movie you might be able to do it. If you are staying nearby and can go back for a break, then for sure you can. There is a nice little movie on Main Street that has a very nice area to look at Disneyland memorablia and is never crowded. That makes a nice midday break too. Good luck!
DLR is 
