When did your DC definitely say his/her first word? Something that was clearly a word and not babble?

DS is almost 9 months, and I swear to God he said hello this morning. We were playing with his phone, and I picked it up and said "hello, you want to talk to Matthew?", passed it to him, and heard this little voice say "Heyyo?" We've played this game before, so maybe he gets it? DS and I thought he said "hi" before too, though less certain since that's an easy babble sort of noise.

I keep thinking he's too young, but given the context, it may have been his first word. Of course we did the phone game several more times, nothing.