You were planning on breeding? If you were, you should have done lots and lots of research beforehand (being concerned about your little pets) and not at the last moment
Is she bigger all around or does she have a bubble belly? If she's pregnant then when she stands up you should be able to see her belly bubbled out. Also, you might be able to see or feel babies moving. To feel for the babies wait until she stands for a treat and lightly feel her belly don't pick her up
. Is she starting to build a nest? Have you given her building materials (peices of papertowel, maybe cut up sheet, or other materials)? Let her build her nest in her spare cage.
As for separating them, I would do it now because she can become pregnant right after
she gives birth (which is VERY harmful to your degu and it's babies), if you wait any longer moving her manually could hurt the babies (when you move her let her climb onto your hand don't grab her around the belly!), and it's almost impossible to know when exactly she will have the babies, most likely you'll wake up one morning and you'll see babies running around and squeaking. Is her spare cage baby degu proof? When the babies are born they're have hair and they're eyes are open (you won't have to clean them) and within an hour they're wandering around. My baby degus were climbing their cage at 1 day old and trying to escape.
Make sure her food and water are close by or on the same level as her nest because once she has her babies she won't have much time to travel around for food. Make sure her babies cannot fall in the water if it is in a dish because if they can they will! Also, make sure there isn't
a wheel around. Remember, the babies will be climbing at like 2 days old so make sure there is nothing they can get hurt on even on higher levels of the cage.
pick up the baby degus. When the babies are about a week old you can put your hand in their cage to climb on and get used to your smell, but don't move it or pick them up until they're a little older. If you rush it and pick them up it could harm them mentally.
There is so much to learn about breeding degus and it is hard to absorb it all in the little time you have. I really wish you had done research first if you were planning on breeding her
. I'll post more info after you reply.