I have (provisionally) booked Meeting Room B for 11am tomorrow.
May I suggest 10-11am on Friday 13th?
Would tomorrow at 4pm be convenient for you?
Would this be convenient?
Would you be available at this time?
Please let me know if you would be available at this time.
Please let me know if this time is convenient for you.
Since we are under a tight deadline, I propose we meet tomorrow morning at 9am to discuss this further. Please make yourself available.
I apologise for the short notice. However, could you please clear your schedule and make yourself available for the meeting?
You may want to anticipate that the reader may not be available on the time and date you suggest, so if you are flexible, you may follow with:
If not, please let me know a couple of alternative dates and times, and I can then check my schedule and let you all know.