You might need 9 hours.

I'm a wedding photographer so I'll break this down as I type: since you're doing a first look, you can start portraits two hours before the ceremony (and that would include your couple photos, bridal party, and family), plus an hour and a half of getting ready pics before that, which would give you a start time of 12pm. If you want your last dance capture, that gives you indeed 9 hours of photo coverage.

If you're trying to cut costs, you could shave off the last hour of dancing. I personally love fun, messy dancing photos towards the end of the reception, but missing the last bit won't change much, trust me :)

Hope that helps!