Introducing a new sibling - small gap.

Just wondering what other mums have done to introduce their first to a new sibling when the gap is small.

My son will be 1yr and 4 months on my due date. He will have a little sister.

He is starting to say words but can't understand much right now. I've been trying to find articles about this online but I only find ones about introducing a new baby to an older child (who can speak and understand things, like 3+)

I'm also conscious that my son may talk later than usual due to being in a bilingual household. So I'm just a bit anxious how I can avoid him being jealous of the new baby, introduce them and help them have a good relationship.

Anyone have any tips or advice?