Cap exempt to cap subject

[IsaacCapExempt]

I got my H1B through a cap exempt organization in 2007. They filed for my green card and I had my I-140 approved last year and am on 3 year H1B extensions now. I have exhausted my initial 6 year H1B. 

I would like to transfer to a cap subject company and am trying to figure out what options I have. 

I know that I have to go back to the lottery so if the cap subject company is willing to file the H1B paperwork in April and let's say I am approved, when I can actually start working for them? Do they have to file for H1B and green card right away so I can start working in October? 

My second option would be to go back to F-1 and start working for them on CPT right away. If I go that route and if they file H1B in April and I get approved, what happens to my Green Card status? Do I lose everything as soon as I switch back to F-1?

I know this is pretty specific so am looking for someone who has worked with moving from cap exempt to cap subject.

Appreciate your help! 

[JoeF]

You can't get an F1 because the F1 doesn't allow immigration intent. Your I-140 shows that you have immigration intent. Besides, no real university gives out CPT from day one. CPT is only for work as an integral part of the curriculum, it is never for working in some arbitrary job.

So, your "second option" does not exist.