Can i Set up uc acount to migrate before appointment with cab i recieved notice

Hello...... anyone,
My partners got to migrate from being in the support group of esa to uc, he's had his notice to do this he's going to phone citizens advice to help him on Tuesday, for an apointment, he's got aspergers and is scared of the whole thing, I'm trying to help as I've been through the universal credit thing. Only it was 7 years ago and different and I went in a job centre and was helped obviously to do it all in there. It's not like this anymore I see, and it would have been better for my partner if it were still like this as it wasn't very difficult. Anyway the form is online I hear which he's dreading being on the spot at the CAB trying to answer questions sous it possible that I can help him set up his universal credit account before he goes to see cab people? Or does it have to all be done on the same day. as this would help a bit with less to do, . Do they ask all about his health condition and how it affects him etc? and for him to work out how much he recieves from pip and things?
I was lucky as like I said a lady in the job centre just did it all for me. I joined here the other day , not sure get a reply,..
the dwp thing gives me nightmares and constant background fear an stress as I am due to retire in 6 months (just when my pip date is said to be renewed, I've been on it over 10 years, I'm hoping I don't lose it as that means being forced to move out and lose help... sorry gone off topic, I just want to help my partner set up his account so he can see it's not so bad and difficult, before he sees a person for help at the citizen advice. Thankyou for reading my ramblings.