A good daycare should be able to go with the flow. My standard advice is to try to have baby in a good routine if possible before starting, but we didn't have JJ in a routine when he started (at about the same age as your DS).
The only thing I'd add is that 2.5-3 hours up seems like a long time to me for a 6.5 month old - so maybe you're having sleep battles with him cos he's overtired (and hitting his 'second wind')? Some babies can go that long, it's true, but it might be something to consider. Yawning is a late tired sign, he might be pulling his ears or rubbing his eyes or getting twitchy a bit sooner. Hope that helps