preparing my toddler for a their first sibling

hey ladies! so I'm only 5 weeks pregnant...but I'm stressing about my lovely 3 year old and how shes going to take becoming a big sister. at the moment I work..but she's stuck to me like glue when im with her. she cosleeps with us as she was breastfed till she was 2...but we r trying to get her into her room. so we are super close...never been one for routines...but feel that I need help now getting her in her room and excited for the baby! any tips please.