I'd post images, but can't on this forum.
Step 1. Go to the internet archive site at https://archive.org
Step 2. Enter phoenix web URL https://playphoenix.online in the archive search bar and hit enter.
Step 3. You will see a timeline of years that represent dates with archived web pages above a calendar. Click on the 2021 link and it will open the calendar with archived pages from that year.
Step 4. When you see the 2021 calendar, you will see some days that are higlighted with circles. Hover your mouse over one of the circles and it will show you dates you can choose. Select a date and it should give you a link to an archived page of the old phoenix web site, if not, try other dates until you find the right one. From there you can simply click on the charplan link at the top of the old phoenix page and it will take you to an archived version of the old char planner.
I don't think the old char planner is 100% accurate to current settings, but it will get you close enough.