Need helpful guide for Exchange 2010/2007 Hybrid setup

I currently have two Exchange 2007 servers, and two Exchange 2010 servers.
We are looking to try and use O365/Exchange Online for migrating mailboxes from both the Exchange 2007 and Exchange 2010 servers to O365.
I'm getting some mixed instructions from multiple people, including O365 support themselves.

Can anyone advise of the steps to carry this out simply?
I believe a hybrid is called "Staged", but articles like this one (https://support.office.com/en-US/article/What-you-need-to-know-about-a-staged-email-migration-to-Office-365-7e2c82be-5f3d-4e36-bc6b-e5b4d411e207) say you can't have a staged migration with 2013 or 2010.

Is there any confirmation on what's supported, and a guide as to how to setup the pre-requisites and configure O365 -- in the right order -- without hosing on-premise mail functionality?

Ideally I'd like some steps to follow to get everything in order, then just simply be able to migrate 20 or so mailboxes at a time from Exchange 2007 and Exchange 2010 to O365.

O365 Support ticket didn't land me much help. Just on hold for 20 mins while a guy e-mailed me a pre-requisite article I'd already seen multiple times which still doesn't give me the in-order steps.