Glad to have you with us.
If you've planted them already (I assume you have) then the foliage will indicate the watering demands (they will wilt without enough water) but even here in zone 7 my irrigation system goes on three times a week so I'd think you're safe.
When you read about not watering them as you plant them, they are trying to avoid rotting the tubers with too much water. Until growth begins the tuber provides everything for the dahlia to grow.
What are the names of your dahlias?
