Follow-to-join for spouse (when principle/primary 485 is pending), and spouse is currently in US under H1B

Hi all,

May I know if there is any case/timeline when apply for follow-to-join for spouse when principle/primary's 485 is pending, and spouse is currently in US under H1B?

if so, do we need to file i-824 form? and how long it generally take for follow-to-join get approved, will the spouse 485 move (get approved) at the same time with the principle/primary's 485?

Thanks a lot for your help!