I have worked complicated and challenging project which is configuring and deploying Office 365 Hybrid and Succeeded recently. I have deployed Office 365 Hybrid on existing on premise exchange 2007 Environment. I have followed below steps to achieve this goal.
1. Install prerequisites software on Exchange 2007 Servers such as Service pack and Cumulative updates which supports for Hybrid.
2. Install Exchange 2013 CU1 on Existing Exchange server 2007
3. Configured Coexistence between Exchange 2007 and Exchange 2013
4. Make sure Auto discover records points to your Exchange 2013
5. Deploy the Hybrid in Exchange 2013 with office 365 by running Hybrid configuration Wizard
6. Test and verify by creating the user account , by moving the mailbox and by mail flow