Welcome to the Uphill Athlete forum.
If you get a Training Peaks Premium account, you have the flexibility to modify your training plan (change dates, skip weeks, repeat, etc.) Last year when I purchased the 24-week plan I got a free month of Training Peaks subscription.
The Basic version will have limited flexibility. It should still allow you to choose a start date in the past so that you can start with the Base Period next week or so.
Hope this answers your questions. Let us know how it goes.