you probably won’t be able to process ALL transactions in one sitting as it does it in chunks of 10K. You will need to process all transactions though. I would recommend figuring out preferred sequence (say, do it annually for each year) ; then once completed your Aug will look hunky dory

Thanks @Karina . But in theory if we didn't have that many transactions would I just have to run it as of August 2023 and it would post all necessary adjustments from prior periods in that month as well? or do I need to go back to January 2020 and post each month separately for the process to work correctly?

IF you did reclassification monthly - yes. HOWEVER you did not; but no need to it each month, just try to see if you can do it annually, so for 2020 do it in Dec 2020, then for 2021 in dec 2021 etc. These are not just revenue plans that get reviewed, the other side is invoices, so I am sure you invoice a ton in 3.5 years