I had another thought to expand on my previous comments. I will still do my itemized planning in Excel to generate a total expense per month. Then I would create Goal envelopes in GB and name them accordingly:
Future: December 2021
Future: January 2022
Future: February 2022
etc.
Fill these envelopes according to the spreadsheet totals. Now when it comes to the last day of November or the first day of December, I would fill my regular envelopes from December 2021 envelope and then delete that envelope and create the next one in the future sequence. That would eliminate having to roll the future months forward in a series of transfers if they were generic buckets like “Next Month”, “Month After Next”, etc.