File immediately...
I would suggest you file for 7th year extension immediately. If your I-140 is denied, your will not be able to apply for extension. As long as your application is pending (which it is even if you have received an RFE), you should be able to apply for extension.
After your H1 is approved, if your I-140 is denied, you will have time to apply for another LC or shop for a pre-approved labor.
I'm applying for my 7th year extension this week.