cell auto-lock after entering time

Hi,

I need some guidance . I'm not too bad with excel but I'm no expert either. I have created a time sheet and I would like to know if there is a way to auto-lock cells after time is entered so that it cannot be changed. As of right now I have employees enter the time by using Shift+Ctrl+;, so the exact time is recorded, however employees can write in whatever time they want. so I guess what I want to do is 2 things:

1- can the cell be formatted to only accept Shift+Ctrl+;, so that the exact time is entered in the cell and prevent employees from entering times they were not at work? and
2- can the cell auto-lock after Shift+Ctrl+; is entered so that they can't modify the time sheet the next day if they arrived earlier than the day before?

I'm not sure if what I want to accomplish is doable.. please help and remember I’m no expert Below is the document i created. Thank you!!!!
Timesheet.Test.xlsx

Simplicity indeed Thank you!!! like i said I'm no excel expert... it is definitely easier to click in and out of the cell but the time can still be modified after its entered... is there a way to prevent this or am I thinking of something that excel is not capable of doing? (I always think excel can do everything my brain can come up with )

thank you you are AWESOME!!!!