Try this
- Name the kind of plan and the amount of notice that would help you decide.
- Explain what you can do when that notice is unavailable, keeping the fallback within your own choices.
A worked example
“For overnight visits, I need a few days to arrange my week. If plans come later, I may need to decline.”
An invented example to adapt, not a real exchange or a script you have to follow.
Before you leave it here
Check whether the requested notice is something you are proposing or a limit you already know you need. Make that distinction clear in the final wording.