Debt planner template will not let me change my Start Month to January 2022. It says you cannot change the date to a future month.
It let me do it on my sheet, so it could be the data validation is messed up.
You should be able to type, “Jan 2022.”
The data validation should look like:
=if(M1>eomonth(today(),-1)+1,false,true)
But also keep in mind, the date should not change from year to year. You want this to be the date you first started the Debt Planner. That way your progress bar and starting amounts will reflect how far you have gotten.
welcome @ashley.blackrn ! 
I just typed 1/1/2022 into the start month and didn’t get the error you mentioned. As @yossiea mentioned, this is the month you want to start tracking your debt payoff journey and if you’ve already been using it for a while, you don’t necessarily need to change it to 1/1/2022. If you’re new to Tiller and just getting started this makes sense and we’re working on getting the community solutions updated with appropriate dates.
I just installed the Debt Planner Template and it does not let me change the date from 1/1/22. I want to change it to 1/2/24 as that is when I am starting. I receive the same message indicated by the OP–cannot change the date to a future date.
I don’t know for sure, but I’d guess that the template is designed such that the start date can’t be a date in the future because a future start date would mess up the underlying math of the sheet.