The way the Cardano protocol works, is by taking a snapshot of the delegation status for all wallets between each epoch. The delegation choice will then become active 2 epochs later, and the rewards will the be paid out after 1 additional epoch.
As an example, the cycle is as follows:
Epoch 220: Stake is delegated
Epoch 221: Snapshot is taken
Epoch 222: Delegation is active
Epoch 223: Rewards are calculated
Epoch 224: Rewards are paid
In this example, you should see the first rewards in the beginning of Epoch 224. The payment schedule is the same for all pools on Cardano, as the payment of rewards is handled 100% by the protocol itself. Pool operators have zero influence on the payments – we simply make the blocks, and the protocol does the rest.