Isla Fisher is releasing her first picture book. The 46-year-old actress – who has children Olive, 12, Elula, eight, and four-year-old Montgomery with husband Sacha Baron Cohen – is already a successful novelist for young adults and older children, but now she’s pitched her talents to an even lower age range. Isla took to Instagram to share a video of herself ripping open a package featuring the books. She captioned the post: “I just received a very special delivery! Here’s me opening the first copies of my brand-new picture book, Mazy the Movie Star illustrated by the incredible Paula Bowles!…