Thank you so much. I was going through the instruction and figured out.You can wait for the email till the date you want to give your test on. There is so such thing as schedule. It's just a link you click and start the test.
You can also call IRCC for the email.
If you still don't get the email. Follow - https://www.canadavisa.com/canada-immigration-discussion-board/threads/december-2022-citizenship-applicants.781857/post-10437046