Welcome to the forum, Raven, Icarus and baby CAG! I would not worry too much about them getting along - at least, not at the beginning because you will need to quarantine for a month before they even see each other. Once the quarantine is over and she is beginning to get used to you, her new home, schedule and routines as well as the better diet, they would have already heard one another for 4 weeks so the very first step is done without you doing anything at all
The most important thing is to keep very faithfully, the routines and schedule you already have for the sun conure and, most importantly, the same amount of one-on-one and out-of-cage time for him. One thing I can tell you, you are going to have your hands PRETTY FULL for the next 2 - 3 years because you will have to contend with both a juvenile becoming sexually mature and a baby first turning into a juvenile and then sexually developing (with the dreaded 'terrible twos' for both of them!) at the same time and I don't envy you this for one single second
