A new baby places extra demands on any household no matter how big or small. It can take a lot of patience, understanding and time for other children in your household to adjust to the new sibling.
It is important that all children in the household are kept to the usual routine that was in place before baby arrived as it worked for everyone but also be very mindful that routines may need to be adjusted to enable the smooth running of the household. One of the things that could be kept in place is if the older sibling is attending creche/preschool continue to have them attend as this means that they will continue to see their friends as normal and the routine as they know it is kept the same. It also gives the parent time to bond with the new baby and get a new household routine in place, if this isn’t an option maybe talk to your child’s creche/preschool to see if they offer reduced hours.
During your pregnancy a sibling can also be caught up in the excitement of welcoming a new baby brother/sister and the excitement can be very overwhelming. There are a lot of books available which can help with the transition of being an older sibling. Talk to them about the pregnancy, discuss names for the new baby, maybe even let them choose (if you dare) and visit friends who have babies.
Every child is different, the way they welcome a new sibling can depend on their age or how many other siblings are already in the family. One of the most common things for parents to do is have a gift on hand when the older child meets baby for the first time, this can help with the bonding of the siblings, nothing expensive just a token. Let them know you love them and that they are an important part of the family.