With staking, coins are eligible immediately. However, they mature over a week(10080 blocks). Until it reaches 10080 confirmation, the weight of the spendable amount is gaining until it reaches the total weight/coin ratio.
Your funds in the wallet are stored in batches called UTXO(Unspent Transaction Outputs)
When you receive funds, it's a new batch(UTXO), and it will stake immediately, upon being spendable, but will need to mature over 10080 blocks (coin age) to be at 100% of its value(weight). It will not impact the other batches.
Moving or sending funds out will potentially break one or more of those batches resetting coin age when creating your transaction. Any change left over from this transaction will begin with a new coin age.
If you reorganize funds in the wallet, like moving funds to an address for creating a masternode, it will also create a new batch—resetting coin age.
If you receive a stake on a batch, it will also reset its coin age.
i.e., at 5040 blocks, 100k Divi will stake like 50k and at 10080 blocks as full weight.