Welcome to the forum.
Can you give us the rest of the sentence in which your fragments might appear? You will find, as you use the forum more, that fragments and phrases need context and full sentences.

Student or Learner
I have to title the option in the backup software.
The option means that user may specify the period of time during which the program will only run.
How should I write it to be correct and official?
1. Only at (a) the time from...to (till)
2. Only for a while from...to (till)
3. Only during the time from...to (till)
4. Your suggestions.
Thanks.
Welcome to the forum.
Can you give us the rest of the sentence in which your fragments might appear? You will find, as you use the forum more, that fragments and phrases need context and full sentences.
Remember - if you don't use correct capitalisation, punctuation and spacing, anything you write will be incorrect.
Write Between xx:xx am and yy:yy pm. "Only" is unnecessary. I used AmE time styles; you should use the style defined by the operating system's settings.
I am not a teacher.
It is the full sentence. This is the name of the option (or the field) in the program. I try describing it in more detail.
You have the program which backups your data. There are the different settings in this program. One of them is ability to restrict the start of program. In other words, a user of program is suggested to specify the specific period of time when the program will run.
So, there are 2 fields "From" and "to" in which a user defines the beginning and the end of that period.
Under those fields the total name of option is required. This name should say if a user checks that option the program will run only during the specified period of time.
I attach the image:
Thanks.
Try "Only allow execution from x to y" or "Only run between x and y"
Only between these times:
[first time] and [second time]
The label above the date checkboxes should say "these days", not "this days".
I am not a teacher.
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