H1b Maxout Options

Hi @Anil_Gupta and other experts here, My Maxout date including recapture days is Oct 28 2022. My employer have filed for perm during first week of march 2022. My husband is on H1b with his i140 approved recently. his visa is valid until April 2023. I am looking for backup options as there is a very high chance that my i140 wont get approved within the maxout window. have few questions

  1. We were thinking to file H4+H4 EAD with a start date of Oct 17 and stop working on that date so that i can legally stay in US after maxout. Is it good enough to file this COS during October first week?
  2. if luck favors , we might get the i140 within maxout. so lets say we file for COS during first week of october and then my i140 gets approved. Will i be able to file an extension based on i140 during this period ( Oct 17 to Oct 28). or do i have to file COS from h4 to h1 ?