This is not a good idea to me because we can never tell when we’ll depart the world. Another thought comes into mind that it is a good idea too but how feasible will it be? The best I assume is by putting the seed phrase of such wallets in a safe in bank since that’s one of the most safest place to store money. You can then use any of your child you wish to first have access to the wealth for the whole family as next of kin. That will be easier and more efficient to work out than locking the funds to a particular time before they can use it.
Using a bank vault is not easier or more efficient and the process of running a timelocked transaction or address is one that anyone with Bitcoin knowledge can try out.
• a bank vault is a third party centralized service, which means you have to trust that they do not open your vault at anytime during when you are using it,
• It costs money to use; th annual fee is not so significant but when you roll over to ten or twenty years it begins to be.
• your country's legality of Bitcoin can change at any point, which means you possibly can have an illegal property stored at the bank.
There are decentralized alternatives at zero costs which you can use.