Movement before serve

[refnrev]

This puzzles me because I have worked with partners who have done this both ways and both insist that they are right. After the whistle and arm signal to serve some officials have made all the other players stay set and still until the serve while others have let the other players move so long as they don;t overlap. Both insist that they are right. I'm so busy with basketball right now I haven't had time to check the book thoroughly. Help me out please.