Without too much notes let's get into it:

Step One :
 Create a wallet you want to send the sats to in the nearest future, copy any of it's address and backup the seedphrase .

Step Two :
 

• Open your wallet with the satoshis
• Create a new transaction on the send tab
• Paste the address you copy into it
• Input an amount you want to lock,you can add a descrioption if you want.

Overview:


Step Three :
 

• click on the "Pay.." button
• Set a moderate fee target
• Click on the preference button to open the preferance modal page and enable the "edit Locktime" because it's dissabled by default.
• Set your block hieght or Date(timestamp) using the dropdown, it's preety easy.

Overview:


Step Four:
 

• Select "preview" to preview the transaction
• check if all the details are correct
• Sign the transaction
• Click on share and save the file or use the Qrcode option to make it even easier for the receiver.
• Finally you can give the file to the person you would love to get those sats when the time reaches in the nearest future.
• Don't forget to give them the seed to the wallet you created in Step one or the private key of the address you  copied because that's the only way they can get it.

Overview:


This can help with inheritance  purpose as discussed in this thread, a lot people might not knowhow to do this using electrum so the thread should help  and:
**Don't worry about them broadcasting it earlier, it will alway be rejected by any node until it reach the time/blockheight specified.
**If you wish to terminate this then all you have to t=do is spend the inputs ou used for the specific transaction, it invalidates it without the input.
**Lastly, don't forget to keep a multiple backups  both the file  & the seed /private key

if you want to know what LockTime is all about read this:
https://learnmeabitcoin.com/technical/transaction/locktime/, pay attetion to the resources.

So how was it? Was it successful?
You can use a short period to test maybe hours to see how it works, if you try to broadcast it at that period it will always return error because it's  normal but the broadcast option will always be active. To test the spending you can do same  but use more thatn one input spend any of it inputs using coin control or spend all, wait till the height or the particular timestamp (the date  specified).
Try to broad cast it again to see your self.
Let me know how it goes.