lakksh is right. If your I-140 is approved by then, you can use your EAD to work. If you are very very lucky, if premium processing is reinstated, you can upgrade your I-140 to PP. So, you will have have your I-140 approved and then you can start using your EAD and AP and maintain the status.
That's what I am doing now. I am not applying for H-1 and instead I start using my EAD and maintain my status. I don't know how far they encourage and approve your H-1 petition when you have applied for adjustment of status (I-485). Think over it!!