This weekend I was Skyping with a friend and her LO who is starting to crawl now (she is 9 months). She recommended that I try spreading his legs far apart and it worked! She also recommended putting a toy in front of him that he could sit at - the tray attached to the bumbo works perfect.
This morning when I dropped him off at daycare, he sat for a couple minutes while I was putting his bottles away. I'm traveling to VA to see family at the end of the month and I was hoping he'd be sitting by our trip - I think we are making great progress! I can't believe our LOs are starting to sit and play.